Here's what I found on the web and in local stores so far this spring:
(note that I have no connection to any of the retailers listed here.
The retailers' table links usually vanish around July 1st and may change before that)

Terms:"side table" indicates short, about knee high, "balcony" indicates tall, about 34"
no height mention indicates full size normal height -- about 28'
** indicates ones I think might work particularly well

RiteAid
**often has small square side tables for $16 or lower that fit the Garden Light patterns. A good practice table for classes.
They also frequently have inexpensive 42" rounds in beige or dark green.
Watch the ads. The suburban stores tend to have both in stock more often than the urban stores.

Ace Hardware
**27" round dark gray (?) $49 I just bought one on-line but they are now unavailable, probably because the color is supposed to be "aged toffee" which was what I got last year. Look for the link to change but the new table to be twice the price and gray.
** brown 42" round $60
** dark gray(?) 48" round $109

Kmart
**42" brown round $79
They also have a number of surprisingly nice tables that are not on the website but you often have to buy the table with the chairs (don't worry about the pattern in the glass)

Sears
also has a number of sets that they don't sell separately: see site/store

Target
many of these are not available in the store, some in the store are not on the web
48" round brown synthetic wicker $199
nesting table set $139
square side table $49
And any of their Tropiji tables

Fred Meyer
52" round brown $99
30" brown with wicker edge $50.01

Pier 1
inexpensive glass rounds:
20" round wrought iron "knots" (base only): $39
20" white curly round side table $50
Scroll dining table (base only) brown 28"+ $150

Lowe's
**dark gray 20" $46 square side table --check weld--
There is a $20 beige side table left from last year and a few larger squares and rectangles that seem to be available only at the store

Home Depot nothing remarkable this year. Sometimes a side table is priced individally, but generally you need to buy the whole set:

Walmart (also has an number of others but the following stand out)
bistro set 24" round table with 2 chairs $98
bistro set 28" round with wicker edge plus 2 chairs $164
http://www.walmart.com/catalog/product.do?product_id=8154049

and, if you are in the Seattle area, also see Rich's and Summer House