If I remember correctly I paid $20 for a visa in PTY. I believe you can also purchase one at immigration in Havana.
Health insurance is mandated and usually $3-5/day when I went so not much you can do there.
Also, USD gets dinged 10% upon exchange (0.90 CUC per 1.00 USD) so if you can aquire Euros at a lower cost, do so. They have 2 currencies (CUP and CUC) so be mindful when paying and receiving change.
If anyone has questions about Cuba or would like recommendations/tips feel free to shoot me a message.
Lastly, don't be a sucker...negotiate 🙂