Re: RG1570 & RG2550 resale question
Very subjective IMHO. Some people would claim that evilbay is a bad place to determine market value. I however suggest going to the bay and searching closed auctions. You can also look in the calssified section here and on other websites to see what people are selling for.
For example, several RG1570 guitars sold sub $500. There was a seller who modded his RG1570 and was trying to get over $600, but noone was biting - and he tried several times to sell it.
Long story short, it is subjecitve due to condition, but the bay is a good place to get an idea of how much is "fair." Also, I think that if you're shopping in a brick & mortar, resale values are typically higher due to smaller market exposure and general lack of knowledge.