Really depends. The greatest value IMHO Is what you personally learn from the exercise, but financially, no. If you don’t like how your speakers are sounding or think you can upgrade for peanuts it’s not worth it.
There are some cases where it’s a bargain. Replacing tweeter caps in Focals and Wharferdales and budget B&W speakers is often worth it, especially if you can find a good sounding, budget cap, like Mundorf MKP (Yeah, others hate them but comapred to Solens I think they are great).
If you feel the need to get your hands dirty, and I wish you would, consider instead building a kit from Madiscound, Meniscus, Parts Express or Solen. You’ll have more fun, feel less frustrated and waste less money.
Whatever you do, consider hanging out at DIYaudio where a lot of excellent and helpful builders are.
Of course, my normal advice is make sure your room has the proper acoustics for your speakers. A poorly treated room will make all speakers sound mediocre and in need of an upgrade. A well treated room will make a lot of speakers sound great.