Hi ncusack,
I can tell you my story, FAA Comm/Multi/IR + CFI. Working to build time in Southern California. I'm also working on the JAA license conversion : 1,795 Distance Learning + 728 CAA exams. You should count on 4,000 for ME/IR conversion + 2,000 CPL license.
That would mean a total of ~8,600 pounds for License Conversion (Minimum !!!).
To get your FAA Comm/Multi/IR will depend on the number of hours that you have. Minimum (you already have 250hrs) would be ~4,000 pounds.
Minimum total required : ~13,000 pounds. And you end up with TWO professional Licenses : FAA + JAA Multi/IR both.
You should maybe double the numbers as worse case. I would say anywhere from 15,000-20,000 pounds to be more realistic.
Again, all that is based on 250hrs of single engine time that you ALREADY have ! If not, add $65/hr times the number of hours that you need to reach the 250hours to the previous number.
Take Care,