Try basspro for fish finder. For under 200 you can get a Lowrance fish/gps. I purchased one last year for my boat and worked great. I just got my 1st boat last summer and can not wait for my 1st time out in spring to catch these walleye. Last summer/fall I only perch fished. 90% of the time I was in gravel pit which is a few miles north of the water intake. Normally look for other boats in that area to find it if your unsure. I fished the other 10% out by shipping channel. Good luck with your boay