As “investment” collectors’ items, IIgses are worth about $20, regardless of ROM revision. You can get five times that if you have a nice specimen and a buyer who actually wants to use it as a working machine. ROM 00 units appear never to count as “nice specimens” to an actual user on account of the bugs that were fixed in later ROM revisions.

Take this with a pinch of salt, as I am about as far from a dealer in IIgses as you can get while still owning more than one, but these are my observations based on very limited personal experience.