.....This is far from the first time a trade for the miniseries has been discussed. The first attempt was derailed by a lawsuit filed by the owners of Charles Atlas' image claiming that the character Flex Mentallo (an obvious parody of Atlas' comic strip advertisements so common in comic books during Grant Morrison's childhood) had damaged the company's reputation. They couldn't substantiate any such injury in court but I have read accounts that DC agreed to pay a nominal royalty rate to the company that now owns Charles Atlas' image whenever Flex Mentallo appears because it would cheaper than continuously defending themselves against frivolous claims. It also means they've avoided reprinting the miniseries.
.....There was once a paperback planned that would carry the ISBN# 978-156389-408-4. Its release was delayed and eventually cancelled. (Some online booksellers note its 'release' date as April 1, 1998; April Fools' Day.) At the time there had only been one DP trade, so Flex' original appearances in Doom Patrol [for one year from #35 (08/90) to #46 (08/91)] had never been reprinted. There was some disappointment, but in perspective the lack of a trade had not yet become a serious issue. That came when the same creative team (Grant Morrison and Frank Quitely) began a lengthy run on New X-Men for Marvel [#114(07/01) to #138(05/03); Morrison continued with art by (variously) Phil Jiminez, Chris Bachalo and Marc Silvestri until #154(05/04)]. During that run John Arcudi and Tang Eng Huat created a new Doom Patrol series [#1(12/01)-#22(09/03)]. Inevitably new fans following either the creators or characters backwards learned of the out of print material. Demand (and secondary market prices) grew.
.....After Morrison left New X-Men two things happened. A Claremont/Byrne story arc in JLA introduced a modernized version of the original Doom Patrol, with the premise that previous incarnations never existed. That led directly into yet another Doom Patrol series months before a second paperback collecting Morrison's Doom Patrol run was published in October 2004. The third, containing the first Flex Mentallo stories, followed in November 2005.
.....Just as the Byrne series ended, Morrison and Quitely returned as a team with All-Star Superman, an erratically published title yielding twelve issues in three years, during which the remaining three volumes of Morrison's Doom Patrol run were published. There was then a gap of almost a year until the Keith Giffen series began, but otherwise the past decade has been continuously overlapping DP or Morrison/Quitely projects even though none of them covered more than a few years. The cumulative effect has kept Flex Mentallo, now fifteen years out of print, on fandom's radar when many of his contemporaries have been long forgotten.
.....The latest version of the promised Flex Mentallo trade is in a hardcover format whose dimensions are somewhere between Golden Age and US Magazine sizes (7- 1/16" X 10- 7/8"). It should be 112 pages for $22.99 (US) with an ISBN# 978-140123-221-4 (or 10-digit 1-40123-221-3). The original release date was solicited as February 1, 2012, but that was changed to Feb. 15 (announced 12/13 on Diamond's website), then changed to Feb. 29 this past week (announced 12/27). Here's hoping that isn't an omen of cold feet again. All I know is that the new date leaves only one month until April Fools' Day.