One thing to measure before you start shopping is the maximum length pole you can get into your kayak. A lot of decisions and DIY ideas can come after that.I was in Trotac yesterday and they had some extendible boat hooks. They were pretty chunky, but seemed really solid. I'm going to paddle tomorrow, but will head in to town and look through some of the stores in the next few days to see what they have. Capital Iron might have something as well.
Unless you can get something really cheap, my advice would be to just buy the REI or MSR poles. I've used them both and they work. The REI poles are sturdy enough and are more compact (smaller diameter tube), as I recall.
If you see used hiking poles in the 'Free' listings or at a very low price, they can be useful sometimes as extenders for other poles.