Ive had my 7's since end of may/beginning of june. They are wearing but at present r8 I think they would last till christmas ( but weather may well mean they last over into the new year).
Considering the cost and life of these hooves. Id say that puts them in the price bracket of an average pair of trainers. I think that is reasonable.
I think bocking should cost between 50p and £ an hour ( excluding travelling & gym costs). So after buying stilts, protection, tyre sox and spring tape add up the cost. Try and see how much you use your kit b4 you need to spend serious money. Though this also depends on 'how' stilts are used. I know a few people learnt quickly and very soon were bouncing the backbone out of their springs. Some have now gone '2up' in weight as a result. So Im talking an average bocker who has purchased the right stilts.