Hi Peter, welcome to the forum. Have you had the expensive test (HCV RNA PCR, Quantitative) 6 months after finishing treatment? If you did and the result was undetected then you're cured and don't need any more tests (unless you're worried about reinfection). If you hadn't, then Dr James Freeman should be answering your question soon.
If, before treatment you had high values for your ALT and AST liver enzymes on you CMP then "proving" cure can really be as simple as repeating just the CMP and checking that your ALT and AST are back in the normal range - if they are down we know that there is no liver damage happening, and therefore there is no active Hep C.
You can get a viral load for about $150 (and under $100 in say Texas) using any of the providers listed here:
fixhepc.com/link2labs - and all but one of these labs will do it WITHOUT a doctors order and give the results straight back to you. Even for routine things like a CMP they are cheaper and use Quest and/or LabCorp collection centres. For example a CMP from www.walkinlab.com/category is $28 and a CBC + CMP is $44 so 1/2 the $88 you've been quoted...