There are several books that I have been waiting for YEARS to turn up on PBS (that never have), and some of those I've "wish-listed" have me so far down on the list that it's kind of pointless.... I wonder if there is a "mechanism" on PBS for folks willing to just loan their books for a short time.  For instance, I somehow waded through ALL BUT THE FINAL BOOK of the Stephen King "Gunslinger" series on audiobook.  I think he's kind of a hack, and care for very little of what he writes, but it is always in the back of my mind that I did the first 6 books of the series, but not the 7th.  I would be glad to send a credit and pay the postage both ways to have it for just the weekend it would take to get through it.... see what I mean?

There is no mechanism for what you describe on PBS, but there is one at your local public library.  Even if they don't carry the book you want, they should be able to borrow it for you from another library via InterLibrary Loan.  Sometimes this service is free, and sometimes there is a nominal fee.

I'm on the WL for quite a few books and it does seem like forever too. And it's almost always part of series, so I won't read any of the others til I have the whole set.

Lately, I've been breaking down and buying a copy (only PBs) from Amazon since I have prime/free shipping. It's about $4 or so for a standard PB and it's worth it if I've been waiting forever and it's the only book I don't have and it's one that doesn't seem to be posted often. Then I can finally read the whole series in order and re-post it together. And I since there's a WL, I'm practically guaranteed that someone will be wanting it right away. It's my contribution to PBS to keep new books entering the system.

Mailing a whole set together costs much less too. In fact, many people appreciate when I've taken the time to collect a whole series and offer it intact.

Well it would be kinda hard for a lot of people to simply swap out an audio CD that sells for $30 - $40 for just 2 credits, so you might be waiting quite a while.  You should probably check out either your local library or audible.com.

There are audiobook rental sites like booksfree.com and simplyaudioboks.com.  You pay a monthly fee to have a certain number of books out at once.  They pay the postage.  If you have an MP3 player you can just load up the CDs the day you get them and then mail them back.  That's what I used to do but I cancelled it because I wasn't listening fast enough. Also I moved to an area with an amazing audiobook collection.

I've taken lately to buying a few books on Amazon - wishlisted books to complete a series, that type of thing. Mostly I can pick up a used copy for $4 (.01c plus $3.99 shipping) . Considering I consider the "cost" of a credit to me is $2.53, the extra $1.50 or so is a small price extra to pay.

There are several sites that "aggregate" info from many sellers.  You can often find HTF books on them, though maybe not at prices you are willing to pay.

Try allbookstores.com, or addall.com.  I think there are others, too, maybe bookfinder????

I have gotten quite a few hard to find books (several years waiting estimate on PBS) from Bookmooch within weeks of posting.  There is less competition there and no FIFO- basically the first person to notice it's been posted grabs it.  If you don't mind checking for your WL books a couple times a day, you might want to rack up a few points on BM (just post a few books nobody wanted on PBS) and give it a try. 

I often pick up the really hard-to-get (at least hard-to-get on PBS) books from Amazon.com or other second-hand sites.  Then after I read them, I usually post them here to get the WL moving faster (or at least get one person off it).