You can look up a price on Jasper's website. Personally I would buy a rebuild unless you want to stay with the original engine. A rebuild would save you less down time rather than waiting to get your original rebuilt.
I myself would go with a rebuild because your original may have non fixable problems and you may end up paying for work that has been done to it up to when they find the non fixable problem.
The rebuild would also have a warranty etc.
I've had good luck with Jasper's engines