Does anybody know where i can get a good cheap marine battery for my trolling motor? I went and looked at Gander yesterday and there cheapest was $90

Check Wally world, they might be a little cheaper.

Wally World. And they are everywhere in case there is a problem.

I use the WalMart Everstart Maxx battery...but it's now $100 for the Maxx model (I got it for less two years ago).  They do have a cheaper model with a reduced warranty period....

If you want good, they ain't gonna be cheap. If you want cheap, Wally world is about as good of a cheap battery as you can get. You can go to some of the local, who knows what brand names they import for China, Korea etc and buy really a "cheap" battery at a cheaper price, but you won't save that much money and in the long run, it will probably prove to be the most expensive one you can buy when you figure the run time and charge cycles you will get out of it.

What size motor on what kind of boat? K-Mart carries Sears Die Hard, Deep Cycle, group 27's on sale for around a $100.

I have a motor guide 30lb thrust trolling motor

There are number of factors you have to consider when buying a TM battery.

Is this a battery that is constantly being set in and out of a boat every time you use it? A good 105 - 120 amp hour battery is going to weigh 60 to 70 pounds.

So, with that in mind, how long do you fish and how far, in other words, how long do you run the TM. Also how much do you run on Max. Max speed runs a battery down fairly quickly.

If you only use it a couple of hours and don't go that far, a smaller, lighter battery will work just fine. You just have to remember, the lighter the battery, the less runtime you are going to get, unless you are running Lithium batteries, but all lead based batteries are dependent on that lead for power, so the lighter the battery, the less lead, the less lead, the less power, which equates to less run time. Before someone jumps in to say AGM's, they are lead based, so the same applies to them. A 45 pound AGM is not going to have much more run time than a smaller flooded cell battery weighing 50 pounds.

If you fish long, and cover a lot of area, you need to look at 105 - 120 amp hour or 225 reserve minutes, however these are very heavy to be handling. Just so you understand, Reserve minutes are based on how long a battery will run with a 25 amp load before it reaches a fully discharged state (approx. 11.8VDC). This does not change, Reserve minutes are just that, whether they be AGM, Flood cell, lithium, gel cells etc so don't think one is going to run longer than the other just because of how it's made. How it's made makes a huge difference in how long the battery last (life span) but not how long it will run the TM.