it's freezing n snowing in philly but i got the E-Go when it was on sale at Fry's for $450. havent tried on the street yet, only in the house.
slow is relative...i havent gone full throttle but i assure you 12mph is very good for beginners. i am a beginner who has never skateboarded in my life so i cant imagine going 20+. it's gonna hurt if you face-plant onto concrete or a car.
the DIY route is very good n you will learn a lot! 1 of the thing that still annoys me is balancing/charging the batteries. i still havent found anything that will do that automatically. on my E-go, it's just so simple....plug in the cord to recharge like a cell phone. no need to rack my brains.
also, there is absolutely no video tutorials on building an e-board from scratch. so if you get all the required materials (about $700 for good single motor driven board kit) and then you find out things are not working out as you read online... you are SOL.
good luck dude. i was in the same predicament as you were.