Are you talking about the Thompson M1927-A1 sub-machine gun chambered in .45ACP, also affectionately referred to as the "Tommy" gun? That's a dead sexy gun, and it's definitely on my "Top 15 Guns to Buy Before the World Ends™" near the top.
You can buy either a surplus World War II era piece manufactured between 1928 and 1945 and pay a ridiculous amount for it, or you can buy a newly manufactured piece made by Thompson Centerfire, the same company that created the original. Here's an example of just such a firearm that's currently selling for $975.
http://www.gunbroker.com/Auction/ViewItem.asp?Item=40286389You can use either tradition World War II-style stick mags, or gangster-style drum mags. Very neat indeed.
When it comes to Enfields, I'd recommend getting an original British Enfield chambered in the cartridge named after it, .303 Enfield. Even though the cartridge is over three quarters of a century old, it still has amazing ballistic properties. With the proper scope, it makes one heck of a cheap sniper rifle.
You can spend anywhere from $100 to $1,000 on an original British Enfield, depending on condition and "history." Generally, you can find a perfectly serviceable Enfield for about $175-$200. You have a choice to make when it comes to Enfields. You can either buy a "re-arsenaled" model that looks great and performs well but has lost some historic value, or you can buy an "original" model that hasn't been touched in fifty years that will look rougher but be worth
slightly more. The cost of re-arsenaling an Enfield offsets the decrease in collectors value, so either model costs the same price.
Because of the overwhelming number of Enfields on the market, they aren't a big collectors piece. As such, I'd recommend buying a rearsenaled piece because they were designed with function in mind, not form. I'd rather have a piece that works and looks great over a piece that is worth more but might not be as useful. Here's an example of a rearsenaled piece. The bore has been re-rifled, the metal has been re-blued, and the stock has been stripped and re-varnished. This is an excellent piece for $199, assuming it sells at that price.
http://www.gunbroker.com/Auction/ViewItem.asp?Item=40293340In the end, it just depends on what you're looking for in a gun, and how much you can spend on a piece.
-b0b
(...will take two, please.)