Yeah a contract is a heavily United States type of thing where everyone wants a warranty on everything they buy, so breeders made contracts that would guarantee the dog's health. Most buyers (even novice ones) will look for a contract with a breeder since many breeders offer one and if you call 5 different breeders you're bound to run into at least one (if not all) that will offer a contract guaranteeing something. So, in an open market, the contract looks like a benefit to have for the buyer. On the breeder side, there is usually something in there about abuse and the breeder having the right to take the dog away, and then if for any reason you can't take care of the dog, the breeder gets the chance to take it back and find it another home.
What you have to ask yourself is how involved do you want to be? Will you take the dogs back if anything happens to the owners? Are you capable of taking care of that many dogs? Do you want the legal liability that comes with having a contract? If you don't want all that headache, then don't provide a contract, but that will show potential buyers that there are other, possibly better, breeders out there and who knows if they would purchase from you.
Breeding is complicated, but the economics behind it are even more complicated. The price, quality, contract/guarantee, and future liability is so intertwined that its not just thinking about a contract, but everything that comes with it. For someone that plans on only doing 2 breedings, how will you replace a puppy if it develops HD or another genetic disease? There are so many more things to think about when it comes to breeding, you should really meet a breeder and get some advice from them, or go through a "breeding cycle" with them and see everything that happens from planning a litter, to having a litter, to always having responsibility for that litter (10-14 years).
I'm not saying that a contract is required, but in my mind, most responsible homes will expect one in this day and age. And when they can go 10 minutes away and probably find a breeder that offers one, you have to ask yourself why would they pick your puppies?