Making one row of results with a batch file?

I have this batch script im working on, the point is to extract certain information from an XML and output the results in a text file. I am able to make it work however, I would like my results to come out in rows.

    @echo off
setlocal EnableDelayedExpansion

(for /F "delims=" %%a in ('findstr /I /L "<XOrigin> <YOrigin> <XExtent> <YExtent>" grid_crawler_output.xml') do (
   set "line=%%a"
   set "line=!line:*<XOrigin>=!"
   set "line=!line:*<YOrigin>=!"
   set "line=!line:*<XExtent>=!"
   set "line=!line:*<YExtent>=!"
   for /F "delims=<" %%b in ("!line!") do echo %%b
)) > result.txt

My Result is

502800
928000
23650
30750

I would like for it to come out

502800,928000,23650,30750

Any help?