I've written about this in the past:
Avatech Utilities Update
Duplicate Mark Values
API Tools Part One - Avatech
First Number Value Template Setup
I also mentioned in one of those earlier posts it is possible to re-number elements using the Element Positioning tool that is available via subscription. Unfortunately it is brutally slow!! On a recent project file it took well over an hour to crank its way through the project database. Frankly it needs a rewrite or fresh approach. It is grossly inefficient to crawl the entire database, generating view by view to establish a selection set. My claims are written like only a "non-programmer" could marginalize the effort to create good code.
How else can we renumber elements, apart from scheduling ingenuity?
Well Avatech's Utilities for Revit are, in my view, unfortunately and arbitrarily limited to Doors, Grids, Levels, Windows, Spaces & Rooms.
Kiwi Codes offers the most elegant solution I've encountered so far. They have two tools; Element Renumber or Category Renumber. Category Renumber is a simple tool that let's you select a single element to define a category to renumber "arbitrarily" and it just reassigns a new number to every element. Keep in mind you'd need to be able to edit every element (potential workset conflict perhaps). Element Renumber lets you set a starting number and pick elements in the order you'd like to renumber them. It also lets you assign an increment value as well as apply a prefix or suffix to the number. For Revit MEP users this tool is a real value, I think. They have a 2011 version, it just isn't on the site at the moment. Write to them.
It strikes me as a bit silly that this sort of tool isn't just part of the software already. I know they've got big list and they are checking it twice even thrice but typically it's the littlest stuff that gets people giggly.
As for pricing of 3rd party applications - I prefer the "a lot for a little" approach. If I were to provide a productive tool for sale I'd be inclined to price it very lightly with the hope that the price is inviting enough to generate significant volume (recognizing the market of Revit users versus the market for selling candy bars...not the same league obviously).
The following statements will rule out my ever being invited to work in sales for these products but here goes. If I were to sell the Avatech tools they'd be about $50. The Kiwi Code tool about $10. The Ideate Explorer for about $35. There are others too but I'll not offend them right now. My rationale is that for these tools to proliferate they need to be a commodity and set at a price that an individual or corporation wouldn't blink at. Especially when they are looking at the capital cost associated with Revit itself. I'm not saying the work of the developers isn't worth more, they deserve compensation for their work.
I'm inclined to think that volume would increase if the price is "right". They'd get a generous return by selling more. The prices I see now are putting up a barrier that makes someone think twice about buying. Maybe I'm full of beans and they are selling like hotcakes but I don't see many of them in use. Then again awareness may account for that more than anything.
[Disclaimer: No product vendors enticed me to write in favor of one or another. This post was born of frustration the other day.]