Tailoring Baggy Shirts/chinos

Upon searching for clothes that fit an athletic build recently, I was recomended to buy clothes a size up and get them altered. Looking online I seen some very reasonable offers for oxford shirts from the like of Ralph Lauren , much cheaper than in the shops.

My question is, If I were to buy say a Ralph Lauren Yarmouth shirt XL could I get it taken into a slim fit oxford shirt, and in the process save cash?!
I have a 17' neck 41' chest and 31' waist and understand that the Yarmouth is the baggiest of the RL shirts.

Thanks for the help!

Anyone??

If the XL fits well in the neck and shoulders & chest, you could have the sides taken in or darts put on the back to keep it trim around your midsection. But making drastic alterations to the pattern always risks throwing off the balance. You may get it well fitted around your 10" drop torso, but then the sleeves could look really baggy unless you take those in well - and then you're spending quite a bit on alterations for an off the rack shirt, and it might never seem quite right (v.s a shirt that was cut for a pattern closer to what would fit you).

I'm sure people may chime in that you should try some other cuts - even in a 'slim' or 'tailored' model and see what will take the least amount of work to make fit. You could also look into 'made to measure' shirts where you can get your measurements factored into the shirt before it's cut. For that option just be aware that it can take a couple tries to get things dialed in, and choosing fabrics online can be a bit tricky.