I know when it comes to switches nothing is better then Cisco but the price tag is way beyond our budget. What can you tell me about some low cost products like Linksys, D-link, Planet, etc? Which of these products are more reliable?
It always amazes me that people jump on a bandwagon of marketing and market share. There are switches on the market that have three times the mean time before failure of Cisco with the same or in some cases better functionality. This does not mean that Cisco products are bad, but rather, as an IT community, there are other factors to consider. The largest problem you are going to experience with the switches is environmental issues. Moisture, humidity, etc., can all render the switches useless, the same goes for your cabling. Your key here is to place the switches in an enclosure or check the components that they are made of as well as the temperature ranges in which they function.
There are industrial grade switches on the market and with the new industrial standards, there are even industrial connectors that are water resistant. Siemon manufactures such a box that gives you additional options for your switches. That said - the next thing you want to address is the mean time before failure of any component that you plan to use, especially in this environment.
Also, since you are planning on mounting them on electric poles with is a HUGE source of EMI, beware of distance requirements from the power lines or they will be flakey at best. I would assume if you are planning on rolling out that number, you would be able to work with whatever vendor you chose to have a hearty version of the equipment on a special run. This will be another key to whom you want to partner with.