Value of mint condition first pressing of Sgt. Pepper?


I have a mint condition first pressing (I think) copy of Sgt. Pepper's Lonely Hearts Club Band.  Vinyl is shiny and plays flawlessly, jacket is shiny with few indentations, and insert looks like new.  Any idea how much it might be worth.  Also, any idea as to how much value something like this gains over the years?  I'm thinking of giving it to my granddaughter (age 4) for her to cash in when she graduates high school.
Any input will be greatly valued.Russ
rustler
Rule of thumb - if it looks like it hasn’t been played it’s probably not the 1st Pressing 😀
Look up the information in the matrix/runout area on Discogs to see what version you have, using the "find your version" tool.  Once you've done that, search the marketplace to see what other people think they are worth.  
I'm with GK on this one. 

As for value, doesn't have to be first pressing to be worth a lot. Just has to sound good. Really, really good. https://www.better-records.com/product.aspx?pf_id=beatlsgtpe_1910_1
thanks to everyone so far.  the album has been in my possession since July of 1967, so geoff's input isn't appropriate.