This is the radiator I got:
www.ebay.ie/itm/TOYOTA-MR2-Mk-2-2litre-R...;hash=item460c21c267
GBP£85 + £35GBP Postage to ROI - you could get it sent to Parcel Motel NI and pay the £15 and the oversized penalty it would save a few bob there
Same seller I used - radiator is still working flawlessly over 2 years / 15,000 miles later
Exact same one mr2-ben sells. As your car is over 20 years old you may need new bushings for the radiator base which aren't included with the new rad - I was able to reuse mine but just to be aware.
I looked at the other aftermarket ones but a good new of them need non-oem shrouds - anyway my cars been round mondello (granted it was a training day) and never passed 9 o'clock on the coolant gauge - the one I linked is allumionum core so supposed to be more efficient
thats my first hand experience anyway
EDIT: heres the post I put up when I changed over the rad - changed the 2 hoses also - probably not encessary but I was minus a car for over a week 200kms from home so needed everything to go to plan:
mr2.ie/mr2-forum/10-general/32937-what-a...&start=120#41083