For me, I think each to their own regarding cost. Prices of stuff is often driven by demand. I paid £600 for my engine and 250 gearbox because it was worth nothing to nobody. At the time, People who owned a 250, their engines were still in warranty and nobody thought they'd fit anything else. I sold the gearbox for a turbo.
The conversion in my opinion saved me money. I was ready to sell cause the clio just wasn't fast enough for me, and I'd exhausted most of NA stuff. The cost to change into something interesting was nearly 3x the cost of the conversion. I think most who traded in their clios actually hadn't fallen out of love with them, they probably just wanted more power.
I'm struggling to let mine go cause it's a car impossible to replace. I'm sure Rouge will end up feeling the same. The advice I'd give is it's not plug and play. It takes a little while to work through the niggles but it's worth being patient.