It's time for a new bike, and I was wondering if it would be worth my time to build my own or just buy one. My budget is $1000. I ride some of every kind of trail. Any advice would be helpful.

building one frame up for under a grand is doable, but you will get more bike for the money if you buy prebuilt.

have you gone to any of you local bike shops and looked around?

Prebuilt is cheaper, but if your looking to customize, thats another game ATG. Abeit, I've seen good deals on parts. ebay

I have and none of the bikes at my local shop come standard with a crankset that is strong enough.

I was thinking of doing a build because I have a trek 820 frame that is still in good shape, but all the other parts are shot. I've been looking at the shimano slx series for my parts, but i'm not sure how to tell if the parts and my frame are compatible.

What ? no bikes with strong cranks.

I would just buy a new prbuilt before putting $1000 into an 820. Atleast if they break (CS), you can get them replace free.

I think that I'm going to go with the trek 4500.

"What ? no bikes with strong cranks."

I will still have to upgrade the crankset. Because of my aggressive riding tecnique I usually bend the rings on the cheap stuff within a week.

https://www.e13components.com/product_supercharger.html

I have a bashguard that does the job. I know this sounds crazy, but try telling that to all the broken cranksets I have sitting in my shed. I just bend the gears when I sprint. If the chain slips at all they are toast.