This may be rough (rough is a speciality of mine), and it uses grep to exclude the start and end label tags. But it works..
~/tmp $ cat test
this is test 1234 wow
this is test 3456 wow
this is test 5463 wow
~/tmp $ grep -v 'label' test | sed -e 's/[^0-9]//g' -e 's/$/,/' -e '$s/.$//'
's/[^0-9]//g' - removes anything that isnt numerical
's/$/,/' - appends "," to the end of the line
'$s/.$// - removes last character from the stream (the final ",")