A quick bit of bash that you can do from the command line on linux (or MacOS, if you have lame installed)…
SAVEIFS=$IFS IFS=$(echo -en "\n\b") let i=0 for f in `ls *wav`; do let i++; lame -h -b 192 $f `printf '%03d' $i`.mp3; done IFS=$SAVEIFS
(The IFS stuff is so that it will work with filenames that have spaces in them)