Two online sources I highly recommend is JUNGS seeds and also RH Shumway. They don't have a huge selection of the newest stuff, but they have a very good selection and they are very very generous with seed amounts and have low prices. They are strictly mail order and the customer service is great....I once couldn't remember the name of a pea I had planted 2 years earlier and really liked and they tracked down my old order and sent me a FREE PACKET.
I think today I'll try some "winter sowing" of foxgloves and verbena. I have never had success with the traditional winter sowing, where you plant the seeds in containers and put them outside over winter in the snow, etc. Last year though, I had a pot sown with verbena that never came up. Instead of tipping it out, I put it in the unheated basement garage and forgot about it. When teh weather warmed up in the spring everything sprouted! So I'm going to try that with foxgl. and verbena again and see if it works. Wish me luck. The week I've had, it will be a miracle the seeds dont come up poison ivy! *HA*