About 50p, I'll be generous and give you £1...
Depends on condition, accessory brands etc but the general rule of thumb is 60 - 70% of everything retail. Some of the Tokyo Marui stuff may (Probably will) bring a bit more money purely because they're TM but again it depends on condition, if they've been modified internally etc
That's going to most likely be a huge hinderance to sales and will also affect prices too sadly