1500 yards isn't childs play. Your gonna have to spend some coin. First your gonna need a good mount. I would check out the Griffin SPRM mount You need a serious mount for a serious scope. Then I would look at the following scopes. They are bit above your price range but lets be honest. If your shooting that far. Money shouldn't be an object of concern.
My first choice. https://www.eurooptic.com/Swarovski-Z8i-35-28x50-P-SR-4A-I-Riflescope-68410.aspx
second https://www.eurooptic.com/Nightforce-NX8-4-32x50-TReMoR3-Riflescope-C633.aspx
Third a little more pricey but amazing https://www.eurooptic.com/Schmidt-Bender-PMII-5-45x56-H2CMR-Scope-666-911-942-G8-E8.aspx
If you really want to go budget you can find these used on Snipers Hide https://www.opticsplanet.com/vortex-razor-hd-amg-riflescopes.html
My first choice. https://www.eurooptic.com/Swarovski-Z8i-35-28x50-P-SR-4A-I-Riflescope-68410.aspx
second https://www.eurooptic.com/Nightforce-NX8-4-32x50-TReMoR3-Riflescope-C633.aspx
Third a little more pricey but amazing https://www.eurooptic.com/Schmidt-Bender-PMII-5-45x56-H2CMR-Scope-666-911-942-G8-E8.aspx
If you really want to go budget you can find these used on Snipers Hide https://www.opticsplanet.com/vortex-razor-hd-amg-riflescopes.html