Aim Surplus and Southern Ohio Gun are good places to go. That's where some of the dealers on Gunbroker get their stuff(then mark it up). Make sure you have a FFL that will receive it for you at a decent price.
There are only two tools you really need: WD-40 and duct tape.
If it doesn't move and should, use WD-40
If it moves and it shouldn't, use duct tape.