Patrick - If you want a restorer to do all the work and hand you a finished product, it will be extremely expensive. If you want to get involved, source some of the product yourself and make some of the decisions on how deep to restore each part, it will be very expensive. If you can source all or most of the parts, do a lot of the work yourself and be involved in all decisions, it will be expensive.
Combine this with what you paid (or will pay) and then make your decision. However, add into the equation that if you get involved, it will be a lot of fun. You will meet a lot of great people and will learn a lot. I am in the middle (?) of the restoration of 4247 GT and even though it has to proceed at the pace my wallet will allow, it is worth every dime. And remember, the GTE market is very volatile. The price it can sell for today will not be the price when you complete the job. Can't tell you if it will be higher or lower, but it will not be the same.
Talk to the experienced guys here or on Tom Yang's site and your will get the information you need to make your decision.
Series III 250 GTE sn 4247
Ferrari250GTE.com & The GTE Register