Sounds like a great deal!
The price: If it is actually a Colt-produced Super .38, one in good shape for $400 is a steal. Some non-Colts used to be marked something like "Super .38 Autmatic Colt Pistol Ctg," from the origin of the round. This was similar to the practice of marking ".38 S&W Special" on the barrel of other brand revolvers.
This pistol: A Colt should be marked with the brand on both slide and frame, and a Hartford, Conn. address on the frame.
If the tag shows "Govt Issue," this is probably an error. I don't recall the
United States government ever issuing Super .38 pistols. Might it have said, "Govt Model" instead? A lot of people call any plain 1911A1-type Colt such, though the Super .38 was not so marked. I'm pretty sure only the .45s were/are marked "Government Model."
If the pistol is a Series 80, you should get good accuracy with little effort. I understand that Super .38 barrels since 1990 have been chambered to headspace on the case mouth. If it is an older piece, it may well be more valuable, but it might take some tinkering to fine-tune it.
The cartridge? As
Doc2005 wrote, the round is closer to a .357 SiG than 9mm. The 130 gr. Super .38 is generally about 100 fps faster than the 124 gr. 9mm Parabellum. Winchester used to offer a 124 gr. Silvertip hollow point, but I don't find it on their ammo site now. It is a relatively easy cartridge to handload, and as it uses .355--.356" bullets, there is a good selection of weights and types. I'm about to begin loading Hornady XTP hollow points in both 124 and 147 gr.
Lay Away: I know nothing of Michigan frirearms law. In Texas, a purchase permit is not required, and a lay away is merely an accomodation between seller and buyer. The federal Form 4473 need not be completed until the time of the actual transfer. There's nothing to prevent a dealer accepting a cash deposit, or a series of payments, to hold the piece until my next payday. Most dealers, though, might not return the deposit, if I failed to complete the transfer paperwork in a timely manner.
Anyhow, I hope you're able to buy the Super .38. If you cannot, please share the location with some worthy person. Like me.
Best of luck
Johnny