I recently got a check engine light with the code P1298

I reset the OBD. If the light doesn't come on again after driving 100 miles, could it actually be fine or have to do with NHTSA #10018077 / TSB #07162005 ?

If I do need to replace it, can I just get the lowest cost "Electronic Load Detector Unit" online that is compatible with a 2000 Honda Accord and replace it myself?

 

Those numbers (i.e., NHTSA #10018077 / TSB #07162005) are not Honda document numbers. It is probably referencing a topic that was part of a August 2005 Honda Service News article. If your driver side under-dash Fuse No. 6 is not blown, then you probably don't have a short in the Blk/Yel alternator wire and that is not your cause. Also, on your generation Accord, the ELD is part of the under-hood fuse panel, and the ELD is not separately sold. A junkyard/salvage yard is an option.