Just to get an idea what's the labor charge look like and materials for a mk3 Gti? Thinking of a half cage.
GREAT QUESTION ~ and perhaps I should have said something to begin with. Back in the day, when Smokestack worked at the shop (good guy, knows his stuff as you guys know), we had a standing deal ~ if you help us build a kit, figure $300 + feed us. Good news, I don't drink beer or alcohol, so its like burgers and brats.
Depending on complexity and materials, I'm kinda hoping to stay near to that. Those were 'easy' cages, where the top came off and we could do something in a few hours (like 4). As long as there isn't any major things ~ like we need certain materials, or a TON of bars, tie ins, diagonals, halo's, frame ties, gussets and all to make it work, I'm hoping to keep to that price(ish). Know what I mean?
For example, my MK1 Jetta. A main hoop, and two back bars with a cross-support above the rear window ~ I'd say that's a $300 job ~ parts and labor.
But lets say you want a SCORE cage. Main hoop, a diagonal in the main hoop from driver head to passenger floor, seatbelt/harness bar, two downs with an X. All in DOM materials ~ ya, that's like over $200 in materials alone. If we are building to a spec, I will want to quote it. That will require seeing the vehicle and the rule book your basing off of.
A simple main hoop with two downward rear bars ~ installed, yeah, $300 parts/labor easy.
A FAVOR: The one thing that will aid in this category, is not making me deal with your mess. Meaning, don't come here with a car full of crap. Nobody wants to wade through yester-year's fast food wrappers left in foot-wells or the back seat.
When I did cages for Cherokee's, I made the participants come with their interior as removed as they could make it. Meaning, the rear seats were already gone, and as much of the crap was out of the way. This makes it easier to build a decent form-fitting cage with as little 'collateral damage' as possible.
Those considering participating should remember that welding creates a TON of heat and sparks. I have welding blankets and cardboard to use as shields, but the more you can get out of the way, the better. Common sense tells us if you come with a car with floor to ceiling purple shag carpeting drenched in last nights AXE body-spray, something is going to catch fire.
I WILL NOT BOLT A CAGE DOWN. I WILL NOT PAINT YOUR CAGE. These are time consuming and costly endeavors, you can do that after we're done and take your time doing it. I'm a family man, doing this as a way to help 'speed' my interior build ~ and maybe get some 16" Snowflakes (did you know they have split-rim snows now?)
FOR INSURANCE AND LIABILITY REASONS ONLY ~ I do not say these are 'roll' cages. Just CAGES. Building and advertising 'ROLL CAGES' implies that they will save your life in a roll over, and I don't want any family members coming after ME for YOU killing yourself while doing something stupid. So PLEASE understand, if we do this, I'm building "SHOW BARS" that MAY OR MAY NOT hold up to mild to severe rollovers. I DO NOT guarantee the performance of the 'CAGE' ~ Only that you might feel special by having one.

That said. I have built SCORE rated cages before. I have YET to have a failure in any cage I've built. Most of my work WILL PASS INSPECTION without any modifications (when built to the standard).