Price sets for Membership

Enabling price sets for memberships has been requested fairly often. I am loggin this to bring the ideas from the module posted here

http://forum.civicrm.org/index.php/topic,14262.msg73978.html#msg73978

into a proper spec.

(10:40:07 AM) dgg: eileen: ok
(10:43:27 AM) dgg: eileen: read thru the posts and the hidden price field approach seems like a bit of a hack to me. If you're up for coding a patch to core for this - i think it's worth investigating changes need to add the membership fee to the price set field feels (for Confirm / postProcess).
(10:44:27 AM) dgg: If you file an issue to yourself - then u and i and lobo can discuss best approach (he might disagree w/ me )
(10:52:43 AM) eileen: dgg - yeah - I'm not sure where the customer will go with this but it's likely they will look at being involved in an MIH on it. There appears to be quite a bit of interest but the current module is pretty hard to maintain so I suspect the others who have implemented it may be quite interested. I find the whole concept of a 'minimum' fee for memberships pretty odd. To me it seems that there is a fee & there there is an additional contribution. To be honest I would replace the existing method with a price set if I could
(10:54:09 AM) dgg: eileen: yeah - not sure the term 'minimum fee' is accurate except in the sense that admins can configure to signups to "invite" additional contribution. i'd be ok w/ just changing that term to "Fee"
(10:55:22 AM) eileen: I find it confusing. But realistically we almost always have to butcher things up to have fee levels of some sort - although membership upsell may make us use separate membership types more often
(10:56:02 AM) eileen: I will log & we can spec it out on JIRA & then I'll see how we can make-it-happen