I definitely don't trust my electronics knowledge enough to order the right parts online to build one myself unless I could get it in a kit form.
Easy Do-It-Yourself build
( HERE )The mega .. ( $23 ) )...
( HERE )The 5 amp motorshield ... ( $45) .....
( HERE ) The Wifi board ..... ( $18) ......
( HERE )The above just plug into each other....plug motorshield into the Mega and the Wifi into the top of the motorshield.
Power Supply .... different voltages.... about $15.
15 minutes to plug them together.... video
( HERE ) ...stop looking where he loads the software the 'old' way and use the easy EX-Installer
( HERE ),
Less than an hour start to stop and no soldering wires.
......and another 15 minutes or less to load the software with the EX-Installer
( HERE ) (menu driven).
Sumner