Pictures and detailed description of every little mark inside and out are required.
Colt 90300 was made in 1914.
Dollar value could be from several hundred to several thousand depending on originality and condition. Change the sights on a pristine 1914 gun and watch the value decrease by 90%. Even a nice US Army arsenal refurbish for WW II or Korea would be worth as much as or more than a new gun. But if Bubba has been working on it, resale value is low and you could treat it like you wanted to with no harm done to history. In which case, it is hard to beat a .45 for home defense.
Study up at Coolgunsite.com where you can see guns from all periods.