It really comes down to two things with TJ lifts- spring quality and the scope & quality of the parts. Some 4" kits are more expensive because they include all upper and lower control arms, adjustable trac bars/etc. All things you'd want to do it right. Take away some of those things and the price gets lower.
So if you are going to drop $700, do some searching for feedback. Also think of the ramifications of what you are doing- if you're going to throw on larger tires, read up on the biggest complaint following that- power loss.
If your Jeep is now currently stock (and not a Rubicon), that $700 would go great towards some locking differentials. Even with factory crap tires, you'll out-wheel lifted guys with open diffs with those lockers. Or a winch- stock Jeeps are lots of fun with just a winch to get you out of trouble.
Just my 2¢. Not trying to be a buzzkill.