Watch when you by ABEC bearings. Your dealing with a slightly flawed rating system and its also used as a name too many times. As far as bicycle hubs go a nicer set of bearings should cost you no more than $30 for both wheels worth. I beleive Formula hubs use a 6000 RS.
If your looking to make them a little quicker you can save money if your tool savy. Pick one of the seals off, flush the grease out. Most bearings come with a ton of grease. Lube them with a really really sticky oil, or really thin grease. A drop of Phils oil works great. Install them with the seal facing outwards. You'll notice the differance.
If your looking for race preformance you can do the same to ceramic bearings, or go a step further and polish both steel and ceramic bearings.