Both BJJ and Judo have their merits. Generally speaking Judo works on stand up grappling and does some ground fighting. BJJ is the other way about normally, in that it works ground fighting quite a lot but only does a small amount of stand up work.
These are generalizations of course. Some Judo schools do lots of ground work and some BJJ schools do lots of stand up.
In terms of cost I have found (as have many other people) that Judo is usually a lot cheaper than BJJ for a number of reasons. BJJ is en vogue right now so people can and do charge quite a bit for it. Someone else on another forum said that a legit BJJ black belt in the USA is probably better value than a college degree right now. I don't know if I'd go that far, but certainly a BJJ black belt teaching in an area where there is no other BJJ close by is never going to be short of a) students b) money.
Judo is cheaper usually. On the flip side, depending on where you live Judo may be harder to come by than BJJ. In North America, BJJ may be easier to find. In Europe, Judo would be easier to find (though BJJ popularity and availability is rising fast in Europe).
BJJ is probably more rounded than most Judo. BJJ classes usually work with the gi and without the gi. Judo works only with the gi (very rare to find a no gi judo class). Additionally, there are some sections of the BJJ community, like the Gracie Academy, Pedro Sauer etc... who teach specific self defence moves. Some people in BJJ question the value of these moves, but it is very rare and explicit self defence moves are taught in Judo. That said, both BJJ and Judo as sports have a lot of practical application for real life physical altercations.
One point people hardly ever make relating to BJJ vs Judo that I am going to say now: In terms of safety, BJJ is 10 times safer than Judo. I've trained in 3 different Judo clubs and every other class without fail someone limps off the mat with an moderate to serious injury. Usually this puts them out of class for a few weeks (or months). This is common in Judo. BJJ seems to be a lot safer, though it can still be dangerous especially if you have poor training partners.
Most people in BJJ who have a black belt have done AT LEAST 10 years of regular training. Some people get it in less time but they are the exception, not the rule. That said, I honestly thinkg a decent blue belt in BJJ would beat about 90% or other martial arts students in a 1-vs-1 situation that involved no weapons. Black belts in most martial arts indicate the student is at an advanced level. In BJJ, a purple belt usually denotes this. A black belt in BJJ is suppose to denote total MASTERY of the system.
Don't worry about belts though. If you go hunting belts you won't get very far. The training you will get the most out of and progress the furtherest with is the training you enjoy. No point in forcing yourself to go to BJJ if your heart isn't in it and you'd much rather got to Judo. I know a lot of folks who thought they "needed" to know how to grapple/ground fight. Thing is, they were kidding themselves a lot of the time. They didn't really "need" to know it. They weren't MMA fighters or law enforcement officers. Outside of class, most of them never grappled or had any use for ground fighting. They believed they needed to know this, but they didn't really enjoy their training.
Go to some classes, and stick with the class you enjoy the most.
Good luck and sorry for the long post.
"Let your food be your medicine, and your medicine be your food"