List of some prepreg companies supplying USA
http://www.compositesworld.com/suppliers/product/294Gurit USA may be of help, it depends how much you need as most prepreg suppliers have a MOQ of 10 or 20m/yrds but also the problem with sourcing from the UK if you go that way is the uncontrolled temperature during transport and duration, if you have a prepreg with an outlife of 7 days and it takes 5/6 days to get there then there is little usable life in it.
Amber composites are pretty good, played with a few but usually subject to minimum order quantities, sometimes you can get 2nds quality but "ya pays ya money and takes ya chance" sometimes its just a few inclusions or weave distorsion every so often but other times the whole thing is pretty much junk.
When you use prepreg then consolidation/debaulking can make the process more labourious than infusion.
You don't always have to use an OOA prepreg, a lot of the time the lower temperature ones such as ambers 8020 and E644/650 are very usable vacuum only.
You will also find voids and bridging more common especially on more complex moulds as there isn't the spare resin to fill them, if you don't force each layer into every nook and cranny then you will have more problems.