What size are you talking? Fruiting Age? What Variety?
There are no set prices for Jabos especially a fruiting Jabo.
If you want to play in the Jabo realm, you gotta pony up the cash, unfortunately.
You can find older trees at the big nurseries (Sabara and maybe Red), but they are pricey.
Much easier to find seeds and seedlings, and be patient.
Check:
Morton and Sons
Green Dreams
Fly Fox Fruits
Barnhill Farms and Nursery
Excaliber
Our Kids Nursery
A Natural Farm
Hope this helps.