not sure what kind of quality that you are looking for... but you can always pick up a cheaper pair at the local Walmart or Canadian Tire... you can get some there quite cheap... I got a pair there 3 or 4 years ago and still have them as my second pair today... if you are just going to use them on this trip, I would just go pick a cheap pair up from one of these locations...
Just my two cents, But get the best you can afford. I have a pair thin canvas that I wore for 8 hrs on the river and have been regretting it for the past two days. I am putting some serious thought into a stiff premium boat after this last trip!
hmm, i've never seen them at walmart or ct, but i'm in sj. the ones i have are great but i bought them in bathurst at a little outfitters shop. they actual matched the price i knew on line, so no complaints.
nothing else has a sole like water walkers, but you could just sacrafice a couple of pairs of sneakers, sandals or boat shoes.