Sorry about the delayed post, I saw this question just now.
You have three options:
1. [For Engineering] Get a low-cost 2D CAD tool (such as TurboCAD), draw what you need, output as DXF and then use a DXF-Gerber converter. You can find decent low-cost converters via Google, the market leader is fairly expensive.
2. [For Manufacturing] Use a low-cost PCB layout tool (PADS from Mentor is an excellent choice) which can not only output Gerber but also do LVS, DRC etc for traces & vias.
3. [For Engg & Manuf] Use a Gerber CAM editor (such as CAM350 from Downstream). This is a bit like drinking neat spirits, but it can be highly effective.
Avoid writing Perl scripts for Gerber output. Been there done that, it's an awful waste of time.
M.G.Rajan
www.eecalc.com