Femara (letrozole) with or w/out IUI??

SF • We have a 5 yo and it took about 4 years of trying for our 2nd, due in July.
I'm 40...I have a 2 yo. We have been trying for #2 for 1 year (I was preg in March but miscarried at 7 weeks). I am going to start on letrozole next week if I get AF (due Sunday). My RE said the IUI will only increase the chance of getting preg by 5%. It's only $215 to do IUI (if I understood correctly). Is it worth the effort for 5%? Thoughts appreciated! Thank you!