Yes, buy the T, 1, and 2 if your budget can afford it. Though, you said gripper being singular lol. so if you're looking for just 1, you could work up to the 1 if you can't close it yet, or rep the T and get better at endurance work.
#3 too, if you really want to get seriously into gripping and going for certs. T=100 1=145 2=195 all in lbs. and the avg. hand strength of a normal man is 120ish? something like that.
The heavy grips, since being cheaper range a little more in the poundages. I've heard that some 300's are actually easier than 250s lol. COC's are fairly consistant and so are Beef Builder grippers.