I have had a look at seedaholics site, and they have a good selections of seeds. I couldn't find their postal charges, so you have to take that into account when buying.
I have used ebay in the past and had very good results, perhaps not as many seeds in the packets, but very often you don't want hundreds of seeds, and usually very competitively priced. One site I use and could recommend for service and value is bobtodd1, and the postage is only 95p no matter how many seeds you purchase and they have a wide selection of seeds.
It can be hit and miss with germination, just depends on how long the seed has been harvested, I sometimes think the larger seed companies have them hanging about for a while and in some cases we have found that the compost is to blame. The quality is not the same now.