If you're desperate to go mitx and you're looking at an H61 board anyway, ebuyer have a
much cheaper MSI board that might be worth looking at as an alternative. You'd need to spend another £8 to get free delivery, but thewn ebuyer have
a range of 8GB DDR3-1333 1.5v memory kits for < £40 which would be suitable for your build too (and in fact, the
i3 2120 is £3 cheaper there too...).
if your total budget is only £200, then I think you're stuck with the i3,
tbh. Even getting the cheaper components from ebuyer you're still going to be spending ~ £75 on the mobo and RAM, and £125 won't quite get you a Core i5 (the 2320 is the cheapest SB i5 and it's £140 at both ebuyer and scan). of course, if you can stretch the budget then the
i5 2320 is a good choice. Ebuyer also have the
i5 2405S in stock for £165 ... it's only a 2.5GHz quad, but with the better HD 3000 graphics core, and a low 65W TDP...
Of course, a lot depends on what you want to use the new box for. If you don't need massive CPU power then a s1155 Celeron or Pentium would only set you back up to £55, leaving £70+ in the budget for a cheap SSD...
Or you might be better served with a Llano build (although mitx motherboard for llano are less common and more expensive...)