Is a firewall on a server an absolute necessity?

[abracadabra]

Hi, I want let my domains be hosted on a dedicated server.

I got this offer by a major hosting company. However, to my surprise a firewall wasn't included in the quote I got from them.

An additional hardware firewall (SnapGear) would cost me an additional $ 99 per month.

Is a firewall on a server as necessary as it is on a home computer?

Or is it only advisable for paysites and when you store important info on the server?

I will only be using the server to submit galleries to tgp's.