For what it is worth, WSU did my dog's TPLO surgeries for right around $2,500 per leg. If Happy's reccomendation is accurate which I presume it is, doing it local will save the hassel and cost of travel.
I hate to say it but for my money on an 8 year old, I would either do the "thread" repair (my brother had this done on the leg of one of his dogs for less than $800) or TPLO if you can afford $2,500 but most likely you should retire the dog from hunting either way. I would probably do the thread repair, retire that dog to pet status, and start looking for a new pup...I think it would be a better use of funds to be perfectly honest.