Shop says my Civic is 'a total if we don't fix it' - should I keep going?

Been through this exact fork in the road twice, and here's how I sort it now. First question I ask myself: if this car were gone tomorrow, would I go out looking for a replacement, or would I just be relieved to stop paying for it? If the honest answer is 'looking for a replacement,' then yes, the repair bill math matters and walking away is fine. If it's the other answer, you're not buying bodywork, you're buying back a car you can't replace, and no quote comparison will ever make that feel rational.

The percentage rule people throw around works okay for flips and for cars with a real market. If repairs run past half the car's fixed value, the money side says stop. But that rule completly falls apart for a car like yours, where the value is mostly that it's YOUR car. There's no formula for that, and the shop guy knows it, wich is prolly why he wasn't pushing either way.

On the hidden-filler problem, budget for the quote to grow by a third before you commit, mentally at least. Once they cut back that wheel arch seam and find the rot travels further along than anyone could see, the scope changes fast. A quote based on what's visible is a starting point, not a ceiling. Get them to agree to call you before each new cut so nothing gets done without your sign-off.

As for the hobbyist body guy doing it cheaper over months, that can absolutely work, but know what you're trading. Money, sure, but also time and risk. Ask to see three finished jobs from the last couple years, not ten-year-old photos, and ask specifically about rust repair, not paint. Paint guys and rust guys are diferent animals. Also expect your car sitting in his driveway while other projects leapfrog it. My own regret story runs the other direction, actually. Sold a beater rather than fix the floors because the numbers didn't work, and ten years later I still catch myself searching listings for it. The car I did fix properly, I've never once regretted the money, even though it made zero financial sense on paper.

First time posting here so hope this fits the thread, but I went the cheap route on my old hatchback a few years back. Did the arch myself with filler over surface rust instead of cutting it out, looked fine for about a year, then bubbled through the paint and was worse than when I started. So if you do find someone cheaper, the one thing I'd check is whether they actually cut back to clean metal or just cover it. Also curious, did the shop say whether the rot is only at that seam or if the other side might match? Mine turned out to be rusting in the same spots on both quarters.

Reading this made me think about my dad's old wagon. He kept putting off the rusty bits for years because the money never added up, and the car just got worse while it sat. Ended up costing way more in the end than if he'd picked one job and done it. So my thougt is, could you just do the one bad spot now and leave the rest for later, or does fixing one area ussually drag the others into it? I don't really get how that stuff spreads once they start cutting.

One thing I'd ask the shop is what the bare minimum version looks like. Not the proper resto job, just enought to seal the seam and stop it getting worse. Sometimes they'll do a decent patch that'll last years as long as you're not showing the car, and it buys you time to decide if you actually want to go the distance. I did that on my old truck, figured I'd sort it properly later, then drove it five more years and the patch held fine. Turns out 'later' was never coming and I didn't care once I was back driving it.

Update: ended up asking the shop for the bare minimum version like one of you suggested, just sealing the rusty seam so it stops creeping. Turns out that patch is affordable and buys me years. Also ran the gone-tomorrow test and realized I'd genuinely miss the car, so when funds allow I'll do the arch properly. Not a resto job, just keeping it on the road.