^^ aftermarket parts rarely ever make the value of your car go up. and if they do, it is only a fraction of what you actually paid for it. you can always do better parting out your car when you are ready to sell it.
the only products that actually hold a fair amount of their value for a car (while still installed while the car is being sold) are wheels and soud systems. this is because there is a fair amount of demand for these products.
most aftermarket parts actually decrease demand for a car...the more modded you go the less of a market you can sell it to--because you are selling to a tuner market, which is much smaller than the stock market. most people do not want a 'hooked up car' contrary to many people's beliefs.
that said, your TRD
shortshifter is $120 (as you say). when you sell your car do you think you can even get $10 more of an asking price having this installed? i would say 'no'.
but if you part out when selling your car, you can sell ur TRD
quickshifter for about $70 (fair), put your stock shifter back in and your car's price will remain the same.