Pro-ject speedbox: Is improvement worth the $ ?

They usually make a very nice difference in sound quality. But it depends on what you have your TT plugged into. The reason speed controls usually make a big improvement is that speed will fluctuate with your AC. Its like a light bulb. You can sometimes see it get brighter or dim at times when the AC varies. The speed of your TT is subject to the same types of variations. If you have a line conditioner that regenerates your AC, you may not need a speed control. A good regenerator will keep your AC at the same level all the time, so if you have your TT plugged into one of those, its probably not necessary to get a separate speed control. Some PS Audio regenerators, like the 500 are known for being used as a dual purpose TT speed control's, as well.

"09-02-14: Devilboy
Hmmm. The table will be plugged into a voltage regulator so it WILL see a steady 120V."

No it won't. For that you need a re-generator.

"All of my equipment draws such little power the output always shows 120V in the display, never going up or down even one volt so I should be good there."

Your equipment isn't the real problem. Varying conditions outside your house make the AC fluctuate. If you call The Cable Company they'll send you a demo speed control so you can try it in your system first.

"About a month ago I decided to get into vinyl for the first time. Since then I've been researching tables, cartridges, accessories, etc. I haven't spun one record yet and already I'm getting the upgrade bug. Started with a budget of less than $500. Today I almost bought a used table that retails for $1,600 new. Oh god."

I thought I was bad. lol. If you haven't even listened to a record yet, you need to stop spending. Get just what you need to play some records and do some listening. The only problem with upgrading now is that you don't know if you're really upgrading. Vinyl is no different than anything else. There's plenty of good stuff out there, but you won't like it all. Just like with speakers and electronics. One thing you'll definitely need to keep in mind, is that if you bought new cartridges, they break in. A lot. More than any other component. Sometimes, new carts sound so bad, you may think its defective. Put at least 50 hours on it before doing any serious listening. 100 is better, but I can tell you won't have the patience to wait that long.