I had the hsg on my second clomid cycle, however, my insurance covered it as it's diagnostic. Had I paid out of pocket I may have waited awhile longer. I think my hsg ran about $1500( don't quote me on it

)... hospital fee and doctor fee. That's just what I recall being submitted to insurance.
Did you just start ovulating while on gluc? How many months? How long have you been ttc? Is age an issue? Those would be some things I would consider before deciding.
As far as the procedure, I had some discomfort, but it wasn't painful. If one's tubes are blocked, I think it becomes painful then.
What type of S/A did your dh have done? The ob that did my hsg, did dh's first s/a and it wasn't as thorough as the one my RE did when we found male factor issues. We 'wasted' about a year due to that. I always like to mention it since back then I didn't really know the difference in tests.
I think it's great that your doctor is being proactive. IF issues can be quite costly though.