I've seen the ego mod around for about 20 bucks, the bolt is usually around twice that. I think the ego mod is a much better deal, the Bolt is a decent PV but their buttons are crap, and at this point in time it's overpriced.
If I had to do everything over again, I would have purchased the egoT mod over the Bolt. One more thing to think about with the egoT mod, you have the choice of regulation or not. You can choose between straight battery voltage, or regulation to 3.2v (or 3.3, can't remember)
While not as helpful as a true VV device this could allow you to tone down your vape if it's too hot, by switching to regulated mode. Or stay in regulation mode and get a consistent vape the entire life of the battery, instead of starting out at 4.2 volts with a fully charged battery, and then slowly loosing performance as the battery drains.
The bolt can also use a Kick, assuming you have some exposed metal inside the tube (I think some of the older ones were painted on the inside so you needed to sand the finish off)
I have no idea if the kick works in the egoT mod. In unregulated mode you are getting straight battery voltage, so if the kick is providing more voltage than a regular battery it should, in theory, go straight through to your atty. But I'm assuming that all the power flows through that little regulation circuit inside the mod, even in unregulated mode, so I'm not sure if that can handle the power.
One more thing, the bolt (in stock form) can't use ego stuff. You either need an eGo adapter or the ego style head for the bolt, usually around 15-20 bucks. And you need an 18650 extension, and you cannot use a single 18350.
The new egoT mods come stock with the new ego style head, so no issues there. There are both 18650 and 18350 tubes available, so you have more battery options, and it's stock form uses 18650s so no need for an extension or adapter.
I'd really suggest the egoT mod over the Bolt. I think it's overall a better device, and it's cheaper. I'm really surprised that the ego mods aren't more popular, considering they are a pretty cheap and very simple entry into the mod world. I think the new style head with an 18350 tube looks absolutely amazing too.