My son is going to Madrid from Boston -mid January. He's not sure when he'll return (June thru mid July). I checked airfare price on Expedia and found a base price of $809. BUT, there is a combined fee of $230.00!!! to change the date of return.
Has anyone got any advice for me on a way to do this w/o a huge fee???

If you want price certainty then pick a date.

If you want date flexibility, then be prepared to pay.

My recommendation is to pick a date 3 weeks after he finishes what ever he's doing (semester abroad?). That will give him ample time to travel a bit (assuming he'll have other time before June). If the return date is really open and is beyond your/his control, then you may be SOL. I'd book directly with the airline myself.

If he doesn't like the date, then ask him to pay to make the change.

When my daughter studied in Madrid (2006), she used STATravel as she could get a $25 change fee through them. You have to get an ISIC card to use them, but it's good for discounts in Europe. I think the STA she used was at Harvard or Harvard SQ.

I used to work in the industry, so I know the answer to your question.

You can buy a round-trip ticket with an open return w/o any additional fees, but you will pay "full fare". That means a cost of a couple/few thousand dollars, depending on the city pair (departure and return cities) and time of year for the departure of the first flight.

Depending on your budget/finances, that means you really are stuck with an excursion fare ticket and with a possible "change fee".

Tell your son to try to pick out a likely return date, and emphasize to him how much it will cost, if he does change it. Maybe if you tell him he has to pay for the change fee, his mind will come up with a realistic return date. Several hundred dollars in a change fee works wonders, in this case.

Something else VERY IMPORTANT to keep in mind: don't count on your having to pay only the "change fee", if he tries to change his return. This is especially true during high travel periods (such as summer vacation time) when flights are almost completely sold out. You will pay only the change fee if seats are available in the original booking class, when you make the change. Since you will probably be booking in a super discounted class when you buy the ticket months and months in advance, it is more than likely, that when you try to make a change a week or two before his actual/changed return date that the super discounted class seats will not be available.

This means you will have to book him in a higher class (of economy seat, for instance)(same seat but higher fare), and you will then have to pay the applicable one-way (half of the new excursion price) fare in that new, higher-priced class. Super discounted seats are limited in number on each flight. This can, in effect, mean you will pay a thousand dollars or so just for the return flight.

Now, if that is not an inducement for him to get serious about his return date when you first purchase the ticket, I don't know what ever will.

I assume your son is going to study and will have a student visa? These are often only issued for the length of the study period, which could affect his return date anyway.
If he is not going to study and is not an EU citizen he will only be able to stay 90 days without a visa. If he has not yet got a Schengen visa he needs to apply for one ASAP.

When I studied abroad (years ago!), I also purchased an open-ended ticket from STA Travel -- www.statravel.com.

The ISIC card is excellent to have.

STA has an office in Cambridge, just give them a call.

<<< My son is going to Madrid from Boston -mid January. He's not sure when he'll return (June thru mid July). >>>

Not without a visa he isn't - most of western Europe, with the main exception of the UK & Ireland - is part of Schengen which basically means that from date of arrival he can only spend 90 of the next 180 days within Schengen (ie visa runs are IMPOSSIBLE).

As he has very vague plans (otherwise why need the open ended flight date), he'll run a significant risk of being denied boarding to the flight, let alone entry to Spain.