I'm about as new as a person can get to veggie gardening, so I was going to make my first venture as easy as possible: simply starting some seeds indoors and then growing them in containers. Is it a bad idea to buy seeds in commercial packets, as sold at Walmart and other stores?
No. As long as you can get the variety that you want at the price you can pay, you will be fine. They all come from the same handful of seed producers, with the exception of the mom and pop "heirlooms".
I use lots of sources for seeds and can't resist poking through the offerings at Wal-mart or Lowes...I've found some interesting stuff by doing so. Prices are good, and germination is usually near 100%. Sometimes something may be 're-named' for their special packaging, but overall, it's a good place to supplement your seed stash.
Farmerdill is right that there's only a few companies that are actually growing seed stock for commercial sales. They just package them with the envelopes that the retail sales company wants.
I got my tomato seeds from one of those racks at the hardware store - plain old garden variety (no pun intended) seeds that are available anywhere, one of those little peat-plug germinators, and just followed the directions on the label.
I planted a lot of them, since having never actually grown anything before, I was expecting a high rate of failure. Much to my surprise, pretty much everything that went into the peat plugs germinated and grew, and I ended up having to give tons of them away to friends and cow-orkers, because I really had many, many more than I could use.
Apparently, when they say on the seed packets that they are "guaranteed to grow", they really do mean that they're guaranteed to grow.
Lesson learned: Never underestimate Mother Nature's ability to compensate for an inept gardener.