used 50D as backup

I'm currently using a 6D and I have my 9-year old 350D as my backup. The 350D is starting to show it's age and I feel it will break anytime soon.
I'm looking for another crop body as a second backup as well as to take advantage of the crop factor for extra reach.
I wanted a used 7D but it's still pretty expensive and the 50D seems to fit my budget. I found one for about $500 with grip, 1 extra battery, 32 GB CF card a 55-250 lens (though I'll probably just sell the lens) and everything else that came with the box.
Is this a good buy? Should I just save some more and get a used 7D?
Need some advice.

Thanks.

Having come from a 50D to my current 6D, I can definitely vouch for the quality that the 50D brings. Here in Canada they go for about 350-500 for the body and goodies, so it seems like the package you're looking at is a good buy.

Between the 50D and the 7D, the AF and general speed of the 7D definitely has the 50D beat. But at almost double the cost of a 50D body, it's up to you to guage whether it's worth it to you. Personally I'm looking to pick up a used 7D as a second body, but not until the 7D2 comes out which should lower the price of the 7D further than it currently is.

I shoot with a MKII and my backup is a 50D. I actually find the build quality to be very similar and bring the 50D out with me more. The shutter is a satisfying 'click' rather than a 'smack' like on the MKII.

I'd say for anything 1600 ISO and below, the 50D is AMAZING. Can't go wrong. And $500 with all that stuff is a steal!

50D is a great camera - one of the better older bodies - has AF Microadjust if you need it.

Thanks all for the replies. Iso1600 is good enough for me because i rarely go above it. And yes, the micro adjust feature is one of the main reasons i'm looking at this model instead of the older 40d.