The best advice I can give for ebay is to be patient. If there's something you especially want, don't rush and buy the first one you see. Instead keep the next few on watchlist, especially if they finish at an odd time of day when people won't snipe them at the last second.
After watching several full boxed copies of the Epic
40k game go for £60-£70 plus ~£10 shipping, I just picked one up for £40 with free shipping