Manifest - how much money are you willing to spend. A few months ago there were a bunch of used HK94's (the semiauto version of the MP5) available for between $2000 and 2800. These were Cal DOJ guns. Most of them were a little banged up on the outside, but bores and internals were generally excellent. If you search the web you may still be able to find a couple of these guns.
Have heard the rumors that Vector is going to start mfg. HK94's in 10mm and .40 configuration, but I'm not sure this has been confirmed. Not so sure about the standard 9mm version. However, those guns are going to run you $1,500. Might be smarter to pony up another $600-700 for a real HK, both because you know it will run right out of the box, and because it should hold its value better if you ever decide to sell it.
The third alternative available to you is to buy a receiver from Special Weapons, and then try to find a parts kit. (POF used to have good quality ones, but they haven't had any in for over a year). You can then have a competent gunsmith build you one. Will probably cost as much, maybe a little more than getting one from Vector, but if you use a good builder (Jayson at IGF is almost universally acknowledged to be the go to guy for HK builds), you will end up with a new gun that nearly as reliable and well made an an original HK.
Oh, you could also wait for the HK clones that Ohio Rapid Fire is going to be producing. You'll know they're about to come out when you see a flock of pigs flying by your window.
I have a Vector 53, in .223, and am pleased with it, will be better when I am more sighted in, but that's another story. Point is vector is coming out with MP 5 clones, pretty well done (in my opinion), in 9mm, .40, 10mm and maybe even .357 Sig.
