We've done the same thing you wanted to. We showed the first year then started breeding immediately. Our first year all our own stock placed in the bottom of their classes and we only won with what we bought. Our second year 5 out of 6 of our market hogs placed first, and the 6th placed 2nd to its' littermate in their classes at county. Their was alot of luck and circumstance that helped us out, but, it was very rewarding to win first, second, and fourth overall market hog, reserve grand champion breeding gilt, and county born and bred at our county, and grand champion heavy weight, and reserve grand overall at district. All out of 1 litter we bred and raised ourselves. You can do it and you can enjoy it, but, if you are going to do this there is a couple of things you need to accept.
1) It is very expensive. Not the best bang for your buck. You're more likely to spend less and win more if you buy from an established breeder.
2) It is very difficult to win with your own pigs out of a sow or two when everyone else is buying pigs that have come out of bigger herds from experienced herdsman.
If your going to do it buy the best gilt you can afford. If you can't afford a good one then wait and save money, or have your kids take out a small farm loan if possible. I hear it helps them establish a credit line and it is low interest. To me their is nothing more important than starting with good genetics. Put structure at the top of your list. Get the help of an experienced herdsman to find you the best structured pig you can get. If she does not do well in the show ring, consider trying to buy the winner (if it has good structure) and eat yours. You might even be able to work out a swap if they are not planning on breeding. It is important to start with the best genetic material you can lay your hands on. If you breed a loser, thats probably gonna be what you show.
On the other hand, if the money isn't the issue and the educational aspect and experience is, go for it and have fun!!!!