Hi there,
I had well over 3 failed IUI's but my FS said generally after three cycles of Clomid then three IUI (in that order I guess) it would be worth going to IVF. We got our 1st BFP on our 1st IVF cycle so I guess he was right all along! I was worried about the cost of IVF v. IUI which was a big difference but I guess you pay for the greatly increased chance of success.

Goodluck with your decision.