A big thank you to Ted Hutchinson (the chap who got me interested in Vitamin D in 2007) for bringing Vitacost to my attention. Their own-brand 5,000iu Vitamin D3 mini gelcaps product is somewhat cheaper than the Healthy Origins product that I've been using ($12.99 vs $14.99). Click http://www.vitacost.com/Referee?wlsrc=rsReferral&ReferralCode=3320491 when creating a Vitacost account, to get $10 discount on orders over $30.
As imports are liable to VAT + handling charges (usually £8) if the value exceeds £15, the lower price means that I can order two pots of 365 Mini Gels for less than £15.
P&P is slightly more expensive at $7.99 vs $4. Delivery takes about two weeks.