Not sure what type of advice you are getting but ... the PS3 is wireless, using wireless standard 802.11b/g - ie 56mbps - so I would imagine pretty much every wireless router will support that as its out for years and if anyone is selling anything slower I would be surprised. The newer 802.11n does speeds much faster but would again imagine those routers are backwardly compatible with 802.11b/g
The PS3 also has a physical ethernet connection so you would get upto 100 meg assuing is a 10/100 card they may have gig cards so even faster ....either way this is pointless as you want to use wireless.
As for the PS3 being fussy as to the router types, again this is incorrect as its just going to make a network connection, for you over wireless. Connect to your SSID, put in your encryption key, set a static ip for your PS3 as you will want that to configure NAT
Now as for "cheap routers like the eircom version" I currently have an eircom netopia that and have it configured to have the NAT set to open, or Nat type 1 - The worst for games is NAT 3 (most restricted), best being NAT 1 where you can play against anyone playing with any other NAT setting, NAT 2 is the intermediate
You configure the router to open up ports to get the different NAT types, recent Medal Of Honor gave a list of ports in the manual that it needed in the NAT settings which I believe are pretty standard with most games now. I already have them set since COD MW2 and they worked fine for MOH and work fine with COD Black Ops