It won't be that hard. Just purchase any PTC script and hire a programmer to implement the CoinPayments API.
And that's it. You can now accept almost every altcoin
If you wants to stick with only bitcoin and other USD wallets then Evolution Script might be the best choice and they also cost only $80 per year offering many great features
Whether Evolution script have integrated bitcoin payments?
Last time, when i look they demo, i not see btc payments like options. I know that some script buyers hire programmers for integrate in Evolution script.
correct me if I'm wrong