Violin shop has 2 sets of price for violins:
For example, a model X violin, if you buy in one payment cost $350; but if you rent to own, the rental to own total actual cost (after numbers of payments) is about $550.
In general, monthly rental is about $25-$45 depends on the quality of the violin. you may try to talk to the violin store and see if they can sell you a lower model (or other instrument, book, accessories) applying the credit toward the purchase.
There is a very informative web site you may want to take a look
http://violininformation.webs.com/