Here's a less than $5.00 item that I use with great success.
A simple racking can along with a #2 drilled stopper.
The racking cane fits very snugly into the spout of a picnic tap.
Place the end of the racking cane into an empty beer bottle with the end touching the bottom of the bottle. Set the PSI down to around 4-5. Open and lock the tap and hold the cork down tight against the bottle neck. The bottle will begin filling and stop when it pressurizes.
Simple push against the cork a bit to allow gas to escape and the bottle will continue to fill (from the bottom) all the way to the top.
Remove the racking cane (CLOSE TAP FIRST) and cap.
Make sure to cut the end of the racking cane at an angle so beer can flow freely into the bottle.
I bottle off a sixer of all my kegs for later consumption. I popped a porter from March and it was perfect.