A simple advice will be to always do a thorough research on anything you want before you part with your hard earned money.I know it's not so easy especially when everything looks so legit these days.Just tread slowly and hopefully you will avoid getting scammed.
To put it simply a "Virtual Office" is like a physical location office that acts as your company mailing address and also includes a local or toll-free phone number.In the same way you can also have a "Virtual Mail" box as well.It's kinda like your "drop" away from your home.Hopes this helps you...
Easy way to do it would be to visit 3 different "branch" ATM's in your country eg.if you were in the USA go to ATM(Chase),ATM(Wells),ATM(BOA) and withdraw $200/$200/$100 on each ATM thus getting out the $500.
just depends for what purposes your're using them for.here's a list for you to check out:
spaceproxy.net / fineproxy.org
faceless.cc / webshare.io
aceproxies.com / luminati.io
brightdata.com / flipnode.io
changemyip.com / geosurf.com
cosmoproxy.com / proxyside.io
dslrentals.com / nonymous.io...