2004 Kia Sedona OBD codes

I recently had 2 different shops (one a dealer) check my diagnostic system and troubleshoot fault codes.
One was a p0441 for evap/purge flow, found the solenoid is defective.
Second was the p0735 gear 5 incorrect ratio and found the in/out sensor to be defective.
Their cost estimate on this job was a grand total of 700.00. I was also informed the trans issue was an exterior part of the transmission and is not included under my 100K mile Kia powertrain warranty.
Can you comment on the costs here and about the warranty issue? Also, what can I expect if I simply do not get these repairs? Thank you.