Using a Sprint prepaid phone (Samsung Galaxy CORE Prime) with Straight Talk?

I bought a NEW Sprint prepaid Samsung Galaxy CORE Prime online for a good price with the hopes of using it with my Straight Talk plan, however, I'm having nothing but issues.

I thought I'd be able to get an unlock code for $2-$3 and all would be fine but that's not the case. I looked into getting the phone "Flashed" but that's $40+ (which means it's no longer worth it to me) and I'm unsure if it'll work.

I spoke with Straight Talk about it and they are unable to help with this issue.

The MEID on the phone starts with: 99000547… If that helps at all.

Thanks!

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