Need help in installing card access control s/m at office.

We are planning to move to a shared office building. There are a couple of other companies. There are about 55 people. I have inquired about the shared network and related (phone, access control) infrastructure.

I want to set up a shared VoIP system. Along with WiFi access points, security cameras, and probably card access control, I'd like to run over a Power over Ethernet network to avoid excess wiring.

I would like to have a simple to administer access control system with proximity card locks on some doors and a system to assign access per card.

Help me out here. We have a budget, but it's not huge, so good value for money is important.