Transmission Error Codes-- Need Advice, Please!

I have an '04 Jeep Liberty with 115,000 miles on it. The vehicle has been driving fine, but a couple of weeks ago the check engine light went on. A dealer and 2 mechanics later, I was told the error codes are transmission-related, and I’m looking at at least $1700 in repairs. 2 of those guys just ran the codes, but the third also checked the transmission pan and said he found a lot of metal shavings, which confirms a transmission problem. Given the mileage, I’m just not sure if it’s worth it to fix. A friend just brought in a code reader for me today, and I found that the codes are P0700 (Trans Control Sys Malfunction) and P0740 (TCC Circuit Malfunction). These do not sound good, but I was wondering if anyone might be able to provide any thoughts on whether this seems to indicate a serious problem, since I’m having no signs of a problem other than the check engine light. Any help would be very much appreciated, as I’m really out of my league here. Thank you!