Well... a reman caliper is not anything different than the replacement of these seals. Just takes a little bit of time. Thing is, I don't necessarily need mine rebuilt, but the rubber is old and worn and since I'm still messing with this spongy brake problem, I might as well eliminate these becoming a problem.
Since I'm doing all 4 calipers, it's not cost-effective for me to replace 'em all for over $200, when I can rebuild myself in an afternoon for less than $20. The TRSM has a very detailed process for this and it doesn't seem that difficult. If I screw 'em up, then I'll drop the extra cash, but it doesn't look necessary at this point.
As far as price comparisons to those seals in the UK, I'd check with Curt (Elmhurst Toyota) or Jeff (Champion Toyota) to see what their price is and if they'd ship them out there. I don't know what auto parts you have out that way, but the kits I have have Beck-Arnley and other partnumbers that you could probably use to order 'em as well (cross-reference).