petco off the top of my head sells penn plax cascade, and eheim ecco..
not sure if they have rena or any other eheims tho, never really paid much attention
If you were to get the Rena XP3, Get it off www.bigalsonline.com. they sell it for $90 + shipping whereas Petsmart/Petco sells it for around $150 - $180.
I just got my order last Friday from Big Al's Online and its all setup and running good.
I got everything for cheaper than what most retailers want for a single xP 3.
Here is how it looked after I emptied the 2 boxes.
Also, the 1L of Efhimech only filled 1/2 the middle compartment of my xP 3 so I'd definitely get 2L at least, if not 3L.