While building and maintaining legacy systems can be a fun challenge, there's nothing economical about it. Like restoring vintage cars, it is a hobby. But while you can modify and beef up an old car to accept a big new engine, you can't really do that with computer hardware and operating systems. If you are going to build a Windows 98 system, you need to use hardware designed to support it. While I do see Win98SE listed on the overview page for that motherboard, I don't see Win98 drivers listed on the downloads page, except for USB support. So you need to make sure Win98 drivers for the chipset, sound, NIC (see Security Note below), etc. come with the board, and for all your hardware.
I see you have listed an add-on sound card even though the motherboard has integrated sound. Note where Turtle Beach Discontinues Windows 98 Support
- and that announcement was 5 years ago.
I found two versions of that motherboard - one includes SATA support the other does not. As stettybet noted, the Delta-L does not. Both boards do, however, appear to have two IDE slots to support four IDE drives.
Security Note: I personally would not attach a Win98 system to a network that has Internet access. Windows98 has virtually no security features and anti-malware options are very limited.
And is it worth the $350-$400 price tag
I guess that depends on why you are building this. For me, no. Absolutely not. I see no reason to build a computer to run an obsolete and insecure operating system. I see no reason to build a computer that immediately restricts upgrade options. Socket A is history. Buying a Socket A motherboard ensures you can only use antiquated CPUs, RAM, and very importantly in this case, AGP graphics cards.
I can see driving an old restored Ford Model-T in your home town parade, but not on a modern Interstate highway. The sad part here is you are not using Windows 98 era hardware so you are not "restoring" a legacy system true to the "era" - so I don't see any value in that. At the same time, you are still selecting legacy hardware, though hardware from a later era (XP era vs W98) - that is, not modern hardware designed for today's OS, specifically 64-bit
Windows 7, or one of the many free Linux alternatives. So I see no value in that either.
Again, it depends on why you are doing this. If solely for personal satisfaction you built a Win98 machine, then I guess, yes. If your goal is to build the best computer for your money, then no.