Request on required devices (preferrably used devices to save cost)

Hi all

I am so crazy about setting up Asterisk or FreePBX based VOIP PBX as replacement of Nortel Business Communication Manager which costs more than 20,000 USD in full complete set of 40 VOIP phones and conference phones.

To propose management as an opensource free low cost alternative, I would like to make sure myself in test lab first on my own money.

At Home, I have one FXO line and will need 4 or 5 extensions. I have one PC on which asterisk will be installed , and I have 3 or 4 analog desktop phones.

The idea is to build one PBX system using FreePBX or asterisk. I do not want to use computers as soft phones or power source.

So I think I would need one FXO PCI card and FXS cards.or modem banks that is fully compatible with Asterisk and analog desktop phones I have.

Please advise me with pricing and devices I would need in minimum cost.