You don't have to have pet rabbits vaccinated if you do not want too or cannot afford to do so.
I've had pet rabbits as a child and we never had them vaccinated and they were very healthy and lived out their lives.
Vaccinating a pet rabbit though is a good idea if you can afford to do so because it protects the pet rabbit from R(V)HD2.
Pet rabbits can be vaccinated as early as 5 weeks of age but you can wait until they are 10 weeks of age to have the pet rabbit vaccinated.