I would probably keep Johnson and not keep Carmona, but either of those guys at $4 is worth a look. I'd say Tulo at $8 is borderline, but since all the good SS in your league are probably being kept you should probably keep Tulo too.
How many teams in this league and what starting positions? If it is semi shallow (12 team), then I would keep KJ ($4) over Drew ($2). Even at $2, I like Johnson, a top 10-12 2B, over an OF probably not even in my top 65.
Below is my squad for 09' as of right now (ext) designates guys I extended for 2009; (m) designates guys that were called from my minor league squad
C Kurt Suzuki C $1/1yr 1B Albert Pujols 1B $67/2yrs 2B Dustin Pedroia 2B $1/1yrs (m) 3B Miguel Cabrerra 3B $46/3yrs SS Mike Aviles 2B/SS $2/1 (ext) CI MI Freddy Sanchez 2B $8/3yrs OF Connor Jackson 1B/OF $3/1yrs (m) OF Shane Victorino OF $1/2yrs OF Carl Crawford OF $40/3yrs OF Josh Hamilton OF $4/1yr (ext) OF U $180
P Mariano Rivera RP $23/2yr P Jon Rauch RP $1/1yr P P Manny Parra SP $3/4yr P Yovani Gallardo SP $2/2yrs (m) P P P P $29
BN BN BN BN BN BN BN BN Franklin Morales, SP, $2/3yrs (m) NA
I'm kind of lukewarm on the others. I like KJ if you need 2B cover when he's an average 2B at worst, but I think you'll be more than fine with Pedroia. Tulowitzki is moderately risky for $8m, but worth keeping over KJ in my opinion.
Can you drop any of those guys on your roster? I would much rather have Tulo at 8 than Sanchez at 8. Pujols at 67? Wow that is tough. Crawford is also high at 40, where he should be at least $5 cheaper.
For the guys you listed, Greinke is a no brainer. Kelly Johnson is in my top 15 2B and should put up double digit SB and HR, $4 is probably just a buck or 2 less than what he would go for in auction. Tulo is a bounce back candidate, and he did pretty well towards the end of last season. At $8 he is still a bargain, as I expect he would go for 12+ in auction.
Greinke is indeed a no-brainer. Not particularly high on any of the others, though you certainly can't go wrong with Drew, KJ, and Byrnes at those prices and you need to save some money on the rest of the offense.
That said, the $67 Pujols is a killer as that is way overvalued in a standard ($260?) league and your pitching staff is likely to suffer for it. You need a couple of quality SPs (at a min) and likely and are going to have to spend whatever it takes to get them. The problem is that means overpaying there in all liklihood and further depleting the money you have left to fill in the rest of your roster. Additionally, you have to factor in auction inflation, which will inflate the prices of the remaining elite players even more than you likely figure. If you could deal Pujols for someone of near equivalence with maybe a $40 pricetag, it would free up some needed cash imo.