regarding g1 prices, id refer to the current AH postings for the color and their color pattern (eg xxy, xyx, etc). some colors are more popular and sell for more, and the AH can be a good judge for popularity+price. also search through forum sales and auction posts for similar (sold) colors/patterns. matching eyes and matchy colors can increase the price somewhat, although this depends on the popularity of the colors. for example, an undesirable xyy avocado/strawberry could probably net you ~400g at most, but an xxy obsidian/x could start at 30kG.

there are some g1 pinglists like g1 hoarders v3(?). im not active in them but im sure there are g1 discords that you could ask for a price check in.

all that being said, if this is an xyz with non-matchy colors that needs some serious scrying work to look decent, its probably just fodder price. eye type and "rarity" of the colors wont really impact the price if its uggo.