If you're looking for an on-line store to buy some inexpensive seeds from that you may not find at your local store view the seed catalog on ValueSeeds.com. I really like their selection that ranges from edible to ornamental plants and the prices are very reasonable. On top of the reasonable prices for seeds I'm really impressed with their extremely reasonable shipping cost.
The usual shipping cost for seeds in most gardening catalogs is what keeps me from ordering seeds. I can't justify paying upwards of five dollars for a couple of packs of seeds. ValueSeeds charges .99 for shipping no matter how large you order is. For about a year I've been following threads about this store on-line and for the most part everyone is happy with their purchases.
Their website is without a lot of frills and the design is nothing to write home about. But the site couldn't be more easy to navigate and they include photos of the plants so you understand what you're buying and gardening zone information. If what I've read about this website is correct this is the outlet for seeds from Thompson & Morgan.
I have to give ValueSeeds five out of five stars for their selection and extremely reasonable prices.