Help with VPN hardware purchase

I need to setup VPN for medical practice. there will initially be a total of 5 users from 5 remote locations.

I see VPN hardware by numerous companies ranging in price from $110 for Linksys Router/VPN to several hundred dollars for manufacturers like Watchguard. What's the difference?? What justifies the additional 300,400 dollars?

What are your recommendations? Bear in mind I near some but not alot of expandability. Max 10-12 users at 6 or 7 locations.

Thank you