The classified section here would be a good place to sell it (Make sure to follow the classified rules)
Pricing is hard as they're not really available any more, however they retailed in Asia for roughly £70... Tokyo Marui do tend to hold better resale value especially when in good condition and boxed (There are TM collectors) but I don't think it would be that much though.
I'm sure somebody with more knowledge will be more help but I would hazard a guess at around the £70 mark still tbh? (As somebody who knows nothing about the TM collector market lol)