International Anti-Aging Systems, located in the UK, sells various patent medications without a prescription. While I'm not endorsing this product since I haven't used it, I've bought similar products from IAS. Several times a year they offer discounted meds and/or free shipping. From their newsletter:

New - Introducing IBSA Thyroid a combination of T3 and T4

IBSA Thyroid is the first synthetic thyroid to combine both T3 and T4 into each tablet and is one of Italy’s most popular thyroid supplements. Each dose is equivalent to providing 21.4mcg of T3 and 74mcg of T4.

Studies have shown that replacement therapy with T4 alone does not ensure euthyroidism -- normal thyroid levels - in all tissues. Euthyroidism could only be achieved by a combined treatment of T4 and T3. Patients consistently reported a preference for the combined treatment and researchers have been searching for specific improvement factors that are clinically measurable.

So far they have identified at least one factor that appears to be related to combination therapy - weight loss.

Research published in the Journal of Clinical Endocrinology and Metabolism reported on a study that found that patients preferred thyroid treatment that included a combination of T4 and T3, rather than the usual T4 only treatment, and that combination treatment was associated with weight loss. This clinical trial is the largest to date, and the first since the Bunevicius study published in the New England Journal of Medicine in 1999 that confirms a beneficial effect of combination T4/T3 therapy.