Aftermarket lumbar support for car seats

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My car doesn't come with any type of lumbar support and because the seats can get uncomfortable for long periods of time (I do a lot of driving everyday), I am thinking of investing in an aftermarket lumbar support. I don't want to spend too much money (maybe around $20). I came across this at Canadian Tire:http://www.canadiantire.ca/AST/brows...p?locale=enHas anyone used these type of products before? Can you please share your thoughts and opinions on them? Any other place that will have a wider variety of these products? (Only found 1 at Canadian Tire)Thanks