I see here about 6 pages, including (home, auth, order creation, history, support and admin order list/order approved) Everything depends on their difficulty, ex support may be chat, maybe only email form. there's  no difficulty with api. Exchange rate is delivered up to your choice, which exchange to use. Currencies list up to you, as well as cryptocurrencies.

The minimum price for a work is 600 usd.
If you wish me to configure cryptocurrencies I will take additional 25 dollars each daemon.
Maximum deadline is month (i have kind a lot of work now)
You pay after work is done, part by part. If you want details PM me.