when was it made and the value of my springfield 1903?

Your rifle was built in 1917. http://www.vishooter.net/SA.txt Your serial # puts it into the "unsafe to shoot" range, (M1903 Springfield Armory serial #'s below 800,000) due to improper heat treating of the receiver. The actual likelihood of a failure is very low, but just so you are aware. (Official records indicate about 4 in 100,000 Springfield Armory built rifles in this serial # range experienced a failure.)

Sporterizing one of these rifles greatly lowers the value. If the rifle is in good condition, I'd also "estimate" the value to be around $300.

MJ has it down pat. Good answer.

I'd like to add though, that my 1903A1 (Springfield Armory) was made in 1912... it too falls within the "low number" range, and has been said to be unsafe to shoot.

Not a problem whatsoever. Don't try running super-duper-awesome-hot handloads through it, and you'll never have a problem. Otherwise, I would say a fair $500 is acceptable for a good condition, low number 1903.

BUT. It's been sporterized. Now it's only worth $300 max.

Pickles, It was originally made somewhere between 1903 & 1917. Unfortunately, sporterizing old, American made military rifles severely decreases their value! Your spoterized version MAY be worth somewhere AROUND 12-$1,500.00. That's a wild guess. Value depends upon a lot of things. Good luck. If you want a better idea, take it to a gun shop that deals in collectible guns or military guns. They would have a good idea.

Sporterized military guns are not as valuable as a full matching numbers rifle, specially of that year. As soon as you butcher it with a stock and aftermarket parts it loses all historical values.

It would probably be worth about 250-350$ would be my guess. You can get them appraised at your local gun shop.