First of all - Bandon Dunes is not going to be cheap and if you are going to do it, I would not try to just skimp by on the cheapest route. To Do it, you gotta do it right.
1. Green Fees - Depending on when you go, Green Fees are going to vary, but if it is summer it will be between $230-250 per round. And if you go most want to get in as many rounds as they can. Expect to play at least 4 rounds. So right there is $1,000.
2. Caddie Fees - I think this was about $100 a round including tip. Not sure if we tipped more or not. So add another $400 bucks here. There are other caddying options, but to me this is part of the experience. At minimum you will be paying about $40 a round for a group caddy that does not carry clubs. But I think it is best to get your own.
3. Lodging - We stay in the cottages, which are four bedroom units that go for around $1600-1800 a night in the summer. You will stay at least 2 nights, so that is $3600 devided by 4. So that would be $900 per person. There are cheaper options where to double beds per room for about $400 a night I think so that could be done at $400 per person. This I don't think matters that much, your choice on where you want to stay.
4. Food/Drinks - Most people stay on site for most things and they have several different options from Fine Dining to Irish Pub settings. We normally do a Pub Night and then a Fine Dining Night. We normally do not get to drunk there because a bad hangover will ruin a day of golf and you are there for golf. Funny how it seems both nights end up costing about the same $50 plus alcohol on food. Breakfast is going to be $10-15 and Lunch is about the same. So depending on what meals you are eating there probably close to another $200 plus alcohol per person
5. Other Activities - I usually only golf, but I know others that go fishing while there or other activities. I don't. But I do get a massage sometimes after walking that much golf in two days. Just something to think about.
6. Transportation - I usually fly into North Bend (OTH)/Coos Bay. Don't waste your time driving from Portland or other places. Time is money and just get to bend. Since I live in Colorado - United flies into North Bend connecting through San Fran. In the past I flew into Coos through Portland on Horizon/Alaska, not sure if they still do it. But I think you need to fly into Coos. Flights often between $500-600 bucks. Can find better deals other times of the week.
Rental Car - we always get a car so that we can maximize our time and have a vehicle incase we want to go into town or do something of site. Three day rental is probably going to be close to $200.
Total Costs - I am guessing it is going to cost about $3000 on the low end and about $4000 on the high end for a two night trip with 4 rounds of golf.