Game music CDs has always been niche and in the current era of streaming/digital soundtracks and the eventual disappearance of CD players, even more so. I think that is the main obstacle in trying to offload soundtracks at a reasonable price in this day and age. Other possible reasons include the prevalence of bootleg/pirate soundtracks being sound in the Western market that drives down the prices of genuine ones. A search for "Final Fantasy soundtrack" on eBay for example already brings up bootlegs in the top ranking results. They are unavoidable and leads casuals to thinking that these represent the "market price" of whatever they're looking for. Another issue is that eBay does not have a dedicated category for "game soundtracks" (that I'm aware of) so it's somewhat of a hassle to find VGM without also bringing up unwanted search results.
As for the topic of "market price of VGM" I generally subscribe to the belief that, outside of popular sought-after soundtracks (like the 3 Super Donkey Kong OSTs) or in-print currently for retail sale ones, there isn't really a market price as such. The selling price of an album is simply whatever the potential buyer feels it is worth at the time. Or if the buyer specifically wants your album, then they will buy it, regardless of price (within reason of course). Whether your album sells at the price you want depends on how long you are willing to wait for the perfect buyer, and how lucky you are. Of course, as you said, if you want to appeal to the casual bargain hunters, then you can easily clear your stock if you price everything at $5, and even then, some albums might not go the first time.
I don't think the game music market is large enough to warrant a price charting tool in the same way as the used game market. The used game market consists of casuals (people who buy recent games and sell them after they're finished) and the hardcore game collectors. In my opinion, just owning a game music album already makes you hardcore.
So what are some actions you can take to sell your load (outside of charging pennies for them)?
1) Take decent or good photos of your albums. Half of the photos on eBay are blurry/unclear or stock photos. The latter is an automatic avoid from me.
2) Describe the condition of the album reasonably. The majority of VGM condition descriptions are generic/auto-filled so you have basically no idea what you're getting. From my experience, even if you have a bad condition item but you accurately state the condition as well as offer an appropriate price, buyers will take it. Better the devil you know, as they say. Needless to say, people would be more willing to pay more for a better condition item. The double-edged sword of course is that this higher price blocks buyers on a lower budget.
3) Play up the fact that your album is genuine, not a bootleg. Once a buyer is redpilled about the existence of cheap bootleg copies and what they are worth ($1 + shipping at best), there's no going back.
4) Sell internationally. With risk comes reward (big $$$). It is often my international buyers that know a good deal when they see one and have the wallet to match.
5) Offer combined shipping. Everyone loves combined shipping and to spread the cost of shipping over multiple albums. This of course works better if you have a decent amount of albums to sell so they can pick and choose.
6) Try to sell your albums in different markets. eBay is obviously the first place any seller goes to sell. vgmdb would be second choice. In third place would be via "social media" or internet forums for specialised topics (e.g. RPG fans, retro gamers, Nintendo fans etc). The latter however, like CD players, seem to be dying out too.
Unfortunately for you, you already do most of the above things, to a higher standard than me even. In this case, I can only suggest being patient and praying to lady luck for that single buyer to come across your listings. There is precedent: me finally selling albums that have been on sale for far too long.
Examples to follow in my next post:
