They’re probably about as cheap as they’re going to get. They’ll go the way of the £5k M5 or £15k 964 soon.
Pre-2009 Boxster i would not touch for bore scoring and IMS. Those cars are ridiculously cheap but most are absolute dogs needing a lot of money. The MY2009 cars are good value with an all new DFI engine. Some good clean low/avg mile MY2009-onwards cars out there. Pre DFI loads of dogs.