Well pretty much my only great deal was, like others, during the great Epic cleansing of the last millennium. Blisters and boxes were sold for £1.00. I can't remember exactly how much I ended up with, but a couple of years back I ventured into my parents' loft to find the ones I had not opened, which was enough to fill a WHFB game box and a BFG game box. The best bit about it was that the store manager couldn't be bothered to count the blisters, so he just gave me the lot for about £15. Sadly, I was only interested in Eldar at the time so I didn't bother to take anything else.
Since then it's gone downhill, I sold off most of what I didn't need not long before GW ditched the minis a second time, and thus "sold the gold before the gold rush" to quote kyuss. Now I am paying through the nose to acquire stuff without any high-value items to trade. The worst part is that I sold off all my 3rd edition Eldar SHTs models intending to replace them with 4th edition sculpts, but I totally forgot to buy them during the fire sale. So now I still need 4th edition Eldar SHTs, which are proving both rare and expensive.

Which reminds me... kyuss, will send you a PM.