P2195 P0138 and Slip Indicator

Help! Looking for some advice. I have a 2011 Tacoma Crew Cab with 6 cylinder engine with about 50K miles on it and both the "Check Engine" and "slip Indicator" lights came on. I attached my scanner and Code P2195 came up. I erased the code and made sure the gas cap was properly connected and drove 15 miles, starting and stopping a couple of times. The "Check Engine" and "slip Indicator" lights came on again and I checked and the code P0138 now came up. What do you recommend? Can I simply replace the Bank 1 Sensor 1 and Bank 1 Sensor 2 devices with ones I can buy at Amazon for about $35 each? Should I buy the OEM parts for $150 each? In the past I attempted to replace the O2 sensor on my 2004 RAV4 and I had a very difficult time getting the bad one out. Or, should I bite the bullet and let the dealer do the work. I would appreciate any advice on this topic. Thanks.