If you went via a fertility clinic for IUI you would only have one insemination per month, and you would use ovulation sticks to make sure it was timed correctly.
Is your donor able to travel at very short notice to make sure you're insemination at the correct time? If you consider that your ovulation test might be negative one day and positive the next, and timing is essential?
Also I mean this kindly but you sound like you're not especially knowledgeable about the process so I wonder how you've met the donor (and why on Earth he's charging you so much money!), what you know about any other children he has fathered, whether you have protected yourself in case he decides to pursue you for access etc.
You also need to look at it from any potential childrens' perspective. Is he happy to be contacted by the child? Will you keep up regular contact throughout their life or just when they turn 18? Will your donor update you with contact details etc when they change to facilitate that contact? Will he facilitate you finding potential biological siblings?
Lots of donor conceived children won't care about any or some of the above, but lots will. Understanding biological heritage is important, even if it is just from a medical perspective.
This is not in any way judgemental, I have donor conceived children myself, but had to go through implications counselling when I went via the fertility clinic, and these are the kind of things they ask you. As you're using a private donor, I'm assuming you won't have had the counselling so the questions may not have occurred to you.
Best of luck with everything 