Last time I diy’d it was triple the cost
I got tools to do other things with after the fact, developed a personal connection with the things I made. The second version didn’t break and was substantially under the original projected costs, but the total was over triple
However, if you want things made to last instead of things to ship these days, the tools and materials of say a decent dining table can easily be under the cost of the product
$500 in lumber, $1,500 for a table saw, $700 for a helical thickness reducer, $700 for a helical planer, $300 for a biscuit joiner, and ~$500 in varius clamps, glues, screws, and materials puts the project at the ~$4,000 mark, which is the starting point for many decent good dining tables (without shipping/delivery)
Idk when your competition is $2,000 mdf with 10 hinges to fit into a 6"×35" box even your finger painting first try has the potential to be a treasured family piece if it can hold up a turkey and table cloth these days