I'm sure you will get tons of opinions on this, it comes up here all the time. Here's mine.
A 6-conversion is whatever you want it to be. The cheapest I can imagine you can do it will probably cost a minimum of $5K - and it won't be very pretty. To do it "right" depends on what your view of "right" is - for me, that would be a conversion that would end up costing about $15K at a minimum.
I've opted for keeping my 2.0L and enjoying it. It's a pretty interesting motor, and I'm probably going to build a 2.4L injected motor sometime just for the hell of it - and it will be a drop-in installation and will probably not cost me much more than $5K by the time I'm done with it.
To summarize - it's worth it if it's worth it to YOU
Brad Anders