They might be ok in a Brit colony... that is your best bet to possibly find a buyer who will bite on numismatic aspect. Those have very high premium 50-100% to find a buyer anywhere else. USA buyers probably won't touch them since 1/4oz gold eagles have much lower markup (although some proofs are listed at similar price... doubtful they sell for that or sell quickly, though). Even in the UK countries, you're likely to have a hard time competing with sovereigns, etc with much lower premiums for the similar gold content - yet still many numismatic options there. You are obviously banking on the little gold Brit's numismatic element when trying to get around $800usd or more for a coin with around $400 melt gold value.
I like the deign also and will buy the silver Brits 1oz bullion when they are a fair price, but their premium is reasonable, low, and in line with their peer silver bullion coins.
I would list yours at double their melt/spot (approx equivalent of $800usd for the 87 and maybe 80% spot aka $700usd for the 88), and then lower the ask prices a bit every month or two if there are no takers? Numismatic is obviously very subjective and dependent on finding a buyer... pawn shops say they are worth melt, some coin shops probably offer you 1.25x melt or less yet ask 4x melt if they sell the same coin, some rare individual buyer collecting proof Brit 1/4 gold might pay you 3x melt if you luck out. You never know with numi.
