I quite enjoy the ± 8.5° tilt that the Canon TS-E 24mm f/3.5 provides. The cost is quite high at around $2,000USD. It seems that some people use lensbaby lenses for something of a similar effect. What lensbaby would most closely achieve the look I am used to from the ± 8.5° tilt of the Canon lens? It is possible that I am mistaken and this effect can not be produced by the lensbaby arsenal, but any direction would be great.
If you want to use the tilt to throw things out of focus, then yes. If you want to use it to bring things into focus (using the Scheimpflug principle), then the Lensbaby optics are not what you want.
All of Lensbaby's optics are designed for special photographic effects rather than straight photography, displaying at least one "major flaw" (spherical aberration over at least part of the lens, field curvature, vignetting, etc.) in order to achieve the desired effect. While their more expensive mount and optics are made of better stuff than the cheaper models, they are still aimed at the special effects market and are designed to have a "look".
Canon (and other maker-brand) tilt-shift lenses are designed for straight photography, to overcome the limitations of a fixed-geometry lens and provide some of the features of a view or technical camera. That includes changing the plane of focus, not in order to minimize it, but to maximize the field of sharp focus in the image, and to correct perspective distortions for things like architectural photography. They go out of their way to provide flatness of field and a very large image circle so that both the tilt and shift can be used to maximum effect. It is only a side effect of the movements provided, used in pretty much the opposite way that they are intended to be used, that you can create some of the effects that the Lensbaby optics are specifically designed for; other aspects of the Lensbaby look need to be added in post-producion.
Edit: Sorry somehow I missed the part about it being a 24mm lens. Lensbaby does not have a wide angle flat field optic. This answer will likely be of no use.
Lensbaby uses lenses with fewer elements and less advanced coatings, image quality will be a factor. The other factor is the build quality. Cannon and Nikon tilt lenses are built very solidly. Lensbaby's lower costs cannot support the same construction methods.
It would apppear as though the best combination of reproducing the look achaiveable by a profesional tilt lens would be with the: Edge 80 Optic with a Composer Pro. The Composer pro does not ship with a flat field optic installed, images produced by it have a circular region of focus. The flat field optic will produce the straight line focus you are familiar with from Canon's offerings.
These two will set you back about 600-700 USD depending on which Composer Pro you purchase.