If you are "in the market" for a market umbrella, the very best thing you can do to save yourself some money and still select from an array of quality umbrellas is shop at Amazon. They have market umbrellas galore.
You can also find market umbrellas seasonally at Target, Sears, and other department stores.
If you are going to shop offline, consider your locally-based retailers. Better to buy from a neighbor than to send your money to some far-away mega-corp. In my town, I can buy market umbrellas from the local garden co-op. Perhaps, something similar is available to you.
You can further save money by keeping an eye out on your local "free stuff" page on CraigsList, and on your local FreeCycle board. You will surely have to be patient, but if you pick up a market umbrella for free, I am sure you will agree it was worth the wait.
Getting market umbrellas at a discount in "the real world" is possible if you are not particular about color. Keep an eye on restaurant auctions in your area. From-time-to-time, you will find one offering market umbrellas.
Finally, if you find a market umbrella available for auction on eBay, go for it!
You will enjoy your market umbrella more if you get it for less!