Hi Yeti,
Welcome to the forum, already one of the busiest threads, good going. I tend to stay with 3 base rubs and adjust if I think its necessary, Cookshack Brisket Rub, Obie Cue sweet rub for chicken and ribs and Bonesmokers for pork. There are sooooooo many choices out there that it is easy to get over eager on your purchases, that was my first mistake I bought about 10 different rubs but only liked 4 of them and realised they dont last very long so now I invest in bulk purchases 7lb plus per rub. The current offerings in the Uk are pretty lame, infact I would stay away from most of them but there will be a few launched in the next couple of months that will take away the problem of shipping from the States.
As an alternative to Kansas City BBQ Store I have always used these guys,
http://www.hawgeyesbbq.com/ the manager is Bret, always very helpful and quick. There are fixed rates on US postal boxes uo to 20lb.
Jackie at American BBQ in Kent also stocks a few types, she has the advantage of shipping them with the large smokers she imports, the web site is
http://www.americanbbq.co.uk/ you will find an email address for her on the American BBQ site.
I placed an order today for a couple of briskets, case of ribs, couple of pork neck ends and some chicken thighs, looking forward to practising competition food this weekend.