Bought the 5150 in 2004 for £800 used with the matching cab, I had actually ordered the 5150II head, but the shop had none in stock as Eddie Van Halen had a disagreement with Peavey and they had to stop making them, so they shop werent getting anymore in (even though it was still on their site), luckily the shop had this original 5150 Mk1 for sale for roughly the same price but with the cab. I sold the cab as I already had the Marshall and was quite fond of it. I've since modded the 5150 (removed the front panel but put the grill back in and reattached the 5150 logo, so you can see the valves glowing behind) and had a bias mod done to run the valves a little warmer (a popular mod to improve the sound).
Pretty sure you can get a 5150 for quite cheap now (probably £400 ish on ebay), not to mention that Peavey have since rebadged and reissued the amp with the 6505/6505II.
As for the little handbuilt, I love it. While it does look a little rough and retro, it has some real quality components and does sound amazing, the perfect practice/recording amp (it only runs at around 10-12 watts with 1x 6L6 power valve). FWIW the amp was built by an amp tech in Kent.