My most expensive gun purchase was either my select-fire HK MP5 in 9mm, or my Auto Ordinance Thompson M1A1 full auto 45 acp. I can't recall what I paid for these 2 of 6 machine guns I acquired over about a 3 year period. It was a lot of fun finding them, buying them and getting out to shoot them. I also enjoyed selling them, as they all went up in value significantly, and I had the fun of fondling and shooting them. The others I owned included:
1. A completely original and correct German MP-40 from WWII.
2. 2 new Uzi's from Vector Arms in Salt Lake
3. A Sendra, the company that became Bushmaster, select fire M-16 style rifle.