Looking to install cd burner

[buzzkiller06]

Ok I have a dell optiplex gx620 desktop and am hoping to install a cd burner for it. Actually I hope to install a cd/dvd burner combo into the computer. I would prefer the drive to be external but the problem is that they seem kind of pricy. So I was thinking about doing it internally but it looks like I only have a 3.5" Drive Bay instead of a 5.25" drive bay that the tower pcs have.

Does anyone know of any external dvd burners that arent too expensive or any internal ones that could fit into my drive bay.

Here is a couple of pics of my computer in case anyone needs reference.

 

[Trotter]

Here's the Dell pages for your computer:
http://support.dell.com/support/edocs/systems/opgx620/en/ug/dindex.htm

here's the page for swapping out your CD drive:
http://support.dell.com/support/edocs/systems/opgx620/en/ug/sddrives.htm#wp1136008

 

[buzzkiller06]

I know how to switch them out, but I dont have a drive that will fit into there. The one I got was for a 5.25" bay while the only drive I can use is for a 3.5" drive bay.