[ale] Simple networking question

[Doctor Who]

I have a Linksys wireless access point with 4 ports.  I'm using it
more as a switch and WAP so that 3 ports are taken up by 2 computers
and one printer and the fourth  goes to my firewall PC.  The
'Internet' port on the Linksys router is not used.

I'm looking to purchase another network printer for this subnet but
I'm 'out of ports' on the Linksys router.  What can be done?  Is it as
simple as getting a hub or switch and having multiple devices on the
network go to that and then have the hub or switch use one port on the
Linksys router?  I'd get a bigger router but other machines have to
connect wirelessly in this subnet (computer in another room).

Thanks for any help with this.  I'm sure there's a simple/obvious
solution but networking is not my forte.