@kaaanonn - I use ebay uk and find that there is a great deal of difference between prices - i have bought several chips and my purchase history shows - Intel i5-3475s for £32, £37 and £25, i3 3245 for £25 and £27.
Waiting for an auction is likely to get a better price than 'buy it now' but there are fewer chips with the HD4000 than with HD2500, so you might find yourself waiting a while for a bargain. I was really happy with all these purchases and still consider that i3 bought for £27 to be a good bargain.
ebay uk currently has several 2nd hand i3 chips, ranging £25 - £100 so it really depends on budget and waiting times. My advice is, if you are no rush, just hold on for an i5 where there are occasional bargains or if you are really lucky, an i7 but my experience is that the i7's prices are much higher. I think the lowest spec i3 with HD4000 is the 3225, and that runs beautifully. If you want to do video editing on your usff then it can probably do that a lot better (and I suspect pretty well too) with an i7.