I work in a company with 3 people who regularly use the same Quickbooks file. However, they work remotely on different networks. I need to implement a solution that allows all three of us to access Quickbooks at the same time remotely (and each make changes at the same time). We have a spare desktop PC that can be utilized as a server.

So, my question is: what is the cheapest and most hassle-free solution to solving this problem?

I've considered using application cloud hosting, however, it is very expensive ($40 per user a month) and we are on a tight budget. Is it possible to install Quickbooks on my own server, and have them connect to it remotely? If so, what is the best way to accomplish this? Remote desktop protocol? Or is there a built in feature for this with Quickbooks Premier 2013?

EDIT: As MDMarra mentioned, I am looking for a solution that offers true simultaneous access. Will using a dedicated server and having users connect to a VPN be a viable solution?