Honestly, the only difference between running no nos and running the juice is instant power. Make a run w/o the bottle, and then turn it on and feel the difference. It's INSTANT. Will things blur outside your car? No. Will you blow blue flames out the exhaust?
No. Will you FEEL the difference? YES, you will. How long does it take to install it? About an hour...Less if you know what you're doing. More if the kit is more complex or you've never done it before. Will it break the bank? No. It won't. Unless you don't follow the directions. Then, you will break something......Which COULD break the bank. Low cost in, and low payments over time. Turbo, you'll have a HGUGE bill up front, and then nothing over tiume. You also won't feel the hp difference unless you let it spool up, then yes, you will feel the difference.
So, Turbo in a 250 hp/250 ft lbs tq max car = 400 hp at the top of the track.....But down low, getting off the line (which is where you need the power in a drag car) you will still have the same power you had before you put the turbo on. 60ft in, you may have full power of the turbo...maybe.
Nitrous in a 250/250 car = 400hp (with a 150 shot) at the top of the track.....However, when you take off the line, you have an instant 150 extra hp on top of what you had before. This follows you down the track.
With all things monetarily being equal (NOS over time equaling out to the same as the turbo) then I would prefer to have the NOS wiht it's instant power off the line. If I were running the car on a road course, I would go with the turbo.