Your collection is all the newest stuff and LEs to boot. If you want some measure of price/value stability you'll need to change your approach and either buy classics that won't be remade (80's classics), oddballs (Joust, Varkon, Safe Cracker), or other titles that are stable (90's DMDs that currently sell for less than what CGC would want to sell remakes for). As others have said, the remakes, VEs, and premiums have generally hurt the LE and upper end resale market.

Also, don't spend money on mods you aren't prepared to lose. You can get some money out of mods but it won't be what you put in it.