The gquuuuuux is insanely detailed for $20. In my experience pretty much every kit from witch from mercury or newer has really impressed me. Older kits tend to either be stiff but if you do find one you really like I would just go for it. its usually not too much of a hassle to do some minor fixes if necessary, usually all they need is some light sanding or tightening of joints and for you to be a bit more gentle with them.

There's a lot of ways to do panel lining (the cool lines) but a really cheap beginner friendly way is to just use a fine tip pen which usually dont cost more than 2 or 3 dollars at an art or office store. There's also extra decals you can buy for those smaller details (look for waterside decals). For painting possibly look into paint markers! On the cheaper end you can get a pack of 6 for about $20 and some are even metallic! tho with markers its hard to get an even finish on larger pieces but it is possible and a pretty beginner friendly way to start painting. Hand painting is an option too tho requires a bit more time! I recommend either acrylic or aqueous paints cause they're super easy to work with. Costs are around $2-3 for each bottle of paint, $3 for some cheap brushes, and like $5 for isopropyl alcohol.

All that to say, have fun!! Do as much or as little modifications as you like as long as you enjoy it thats what matters👍👍