Because I charge in BTC & altcoins and their prices keep changing, that's the reason for not putting price publically as it has to be adjusted with market conditions.
Well any popularly known or unknown VPN services you use they after all using servers from some host like you will do, your data is still under the watch of the host where any popularly 'KNOWN' VPN is hosting servers. It indeed is far more secure using your own VPN servers and it costs less cheaper thank paying hefty monthly fees and you get amazing speed which usually not stable with any good VPN provider as they end up with overload of network traffic from users' usage.
Anyway, nevertheless it's choice of the individuals to decide what is best for them.
If the price keeps changing then you charge in fiat, it's not that complicated. If you charge in BTC then there is no change as 1 BTC = 1 BTC
Secondly,
a lot of VPNs have a no logs policy which means no information is stored, so don't talk about your option being "far more secure" because it's actually not. As for the speed, I agree it certainly is faster having your own VPN, but claiming that other providers are "unstable" is just not true. Most of the well-known services are fast and have a bunch of server locations, couple that with the no logs policy and you are better off paying the "hefty" monthly fee.
Again, I do not mean to insult you, but you are offering a service regarding privacy and I feel there is no room for error and misinformation on this topic, everyone deserves to have their privacy.