Help finding steel frame disc brake bike

So, I am attempting to build a commuter bike. From what I've read here and online elsewhere is that a mountain bike, hardtail, would be preferred made of steel with disc brakes. I am having a hard time finding this kind of bike. My price range is around $400 for the bike, new or used.

My current set up is a cheap Walmart Roadmaster with a rear geared Ampedbikes kit with Ping 36v 10ah Lifepo4 battery. I will be getting another 36v 10ah battery because my daily commute will be a total of 22 miles.

Any suggestions?

*Edit: Roadmaster 26" tires and I'm 165 lbs and 6'2". Online, it says a good size frame from me would be 20.5" with crank size 180mm for what that's worth. Thanks!

http://www.walmart.com/ip/26-Mongoose-Ledge-2.2-Men-s-Mountain-Bike-Orange/22861843
I've got the 2.1, which doesn't have the front disc brake. Frame is aluminum, but swing arm and dropouts are steel. A 2.4" Cyclops tire on a 39mm rim is a tight fit on the rear, but it fits. I assume the 2.2 is the same.
And thens there's this.
http://www.academy.com/shop/pdp/mongoose-men-s-dolomite-26-7-speed-fat-tire-bicycle/pid-1038954
I've been procrastinating buying one for a few months now and putting a 3-5kw motor on it.

Do you want a rearmotor or a front motor? If you get a front motor, frame can be any of the material, steel, aluminum,etc. Just make sure fork is steel and motor has disc mounts. If said bike doesn't have steel fork with disc tabs, buy a fork that does.

such as this... http://www.nashbar.com/bikes/Product_10053_10052_174928_-1___204715

if you don;t have a bike yet, choose one of these frames....http://www.nashbar.com/bikes/CategoryDisplay?catalogId=10052&storeId=10053&categoryId=204685&langId=-1&parent_category_rn=204647&top_category=204647&pageView=

for $99 you can get a decent frame, I got the nashbar aluminum mountain bike frame for $99. If you get all the needed componets, you will be close to $400 fiqure.This is without the price of the electronics. Look at the 24 inch frame for $25. Want it less attracted to thief, maybe get a girls frame.

A steel bike could have a disk mount welded to it. But your best bet might be a compromise. A good aluminum frame, with rear disk, or a steel frame that can have a nice disk brake shock fork put on it. (1 -1/8 headset)

So if you go steel, you'd have disk front brake, and rim rear brake.

I've said this before, but I still like these bikes.

http://endless-sphere.com/forums/viewtopic.php?f=3&t=49081&start=25#p732574

No rear disc mount, but rim brakes on the rear perform very well, or you can mod the frame like these guys have. It's not that tough.

You can shop around on C-list and find these bikes for as little as $100, and if it's a 36V, you can sell off the controller and motor, yielding sometimes a zero initial investment.

I have way too much EVG and Crystalyte stuff lying around, including frames, motors and controllers, pretty much everything but batteries at the moment. If you can't find a solution, PM me, maybe we can help each other out.

Look at CFG on Amazon. Steel frames, all sizes less that $100. and with some of your existing components, way less than $400 for a complete.

Thanks for all the feedback! I didn't know that aluminum bikes with steel drop outs were an option. I still want to go with a rear motor. Not sure what CFG stands for? The bike that I have is short for my size and has many issues I need not go into. I will let you know if I find a candidate and post here.

CFG is sold by Amazon, and I don't know of any other retailers for this brand. The only person that I know of who bought one showed some pictures of the frame. It came in a Bike Nashbar (check them on the web) box and was heavy (7.5 pounds for a 29", L steel frame), but if it's consistent with the products I've purchased from them bulletproof and a great deal.

How about a Surley chromo disk fork on just about any old bike? And the front motor of your choice?

There are Plenty of Steel , Mountain Bikes with Disc Mounts, everywhere !

You just need to know what to look for ,

Back in the Late 90's and early 2000's there were many companies making mid and high end Cro-Moly , double butted, cross country mountain bikes, many were made to ride almost like a titanium high end racing mountain bike .
Compaines like Jamis, Gary Fischer, Kona , are just a couple, I have a Jamis made in 2000 and it looks like a titanium bike , with no paint, it also rides almost like one, back in the day I test road every titanium mountain bike I could , the big names, Lightspeed, Moots, etc. and a good Jamis, Kona , is almost the same, find one from a part of the country that has a low amount of moisture, also one that has been sitting in a garage most of its life,
I got my Jamis, with very little miles on it,, it has 9 speeds, which is a good sign for that year as it says it was a upper mid range price bike, since I repack the bearings myself , the hubs still spin like butter !
and it has over 5 thousand miles on it. All Shimano Deore parts, and they still work,
Forget about cheep steel bikes 1 , the price on these , around 14 year old bikes is so low that you can change out many of the parts, and the good ones with 9 speeds also have the 1 1/8 threadless headset, so you can get mail order a good modern fork with disc, not only that , Performance Bike Shop, sells a good Forte Disc 26 inch wheelset for a very low price , considering it has sealed bearings, and great reviews .
Go Retro and get a Jamis, or Kona , or Gary Fischer !

Hi,
Where do you live in Boston? I saw some bikes on clearance at REI in Fenway, they had a big Bike sale last weekend, I bought one there , I saw mountain bikes in 400$ range. I dont think you need steel dropout on a 36 volt geraed rear motor. I have aluminum dropout on all my bikes, geared and DD , I use up to 60 volts.

I live in Boston and have a few bikes, if you want to try one of my bikes PM me .

I've taken the plunge! Going against my own post, I bought a used Fuji aluminum bike 22" frame with V-brakes for $150 on CL. There was a Jamis for $300 21" frame but the OP keeps changing the price and now it's $400. I am happy with my purchase and I think I can make the brakes work? Here's a pic of the new bike I plan on working on.