There are no top quality Terry's in the UK (AFAIK), so if you need the best buy Megs. If you just need them for sills, engines, door jambs etc. buy a 50 pack from Costco for about £11.50 or so & throw them away when they get too grubby to wash.
I haven't come across any top quality MF's that you can source from the UK. That's why I have bought AG Group, Australia (fabulous MF wash mitt), Pakshak & DF (both USA).
The Megs UW is ridiculously priced at £9.99. Even with carriage & VAT etc all the Australian & US orders I have had are much cheaper (& better).
I have now built up my MF collection to over 30, but I do have 3 cars to keep clean!