You never mentioned how big your transparencies needed to be;
There's only 4 options currently available for making transparencies (I call them all "film") Most economical to expensive are:
Inkjet - This is the cheapest and most inexpensive as far as initial investment to get in to. The drawbacks are that you don't automatically get postscript with the printer so you may need a 3rd party RIP. A good solid black depends on who's ink you're using. It can be painfully slow to print larger images and clogged heads do happen. This can interupt production. You can spend anywhere from $50 for a small desktop unit to well over $10,000 for a wide format printer. Most films are not moisture proof. So you have to handle them carefully and keep them away from the wash out sink. A few of the vendors recomend spraying your films with artist's fixative after they've dried to help protect them. I agree with Roadside. There are lots of other vendors besides US Screen and their Fast(bucks) Films (disclaimer: I've had issues with Scott Fresener - see
www.tjetsucks.com).
www.squaredot.com has a better priced product and good support. They also have a very inexpensive RIP.
LaserPrinter - Like the Xante. The films suffer a bit of shrink and distortion because of the fuser. Xante has built compensation controls into it's driver to counter this. You don't get a good black without running it through a black enhancer (liquid processor). Last time I checked, The Xantes started at about $2000 and up. You don't have to buy Xante, most all laser printers will do. But you have size limitations. A unit that does letter and legal are really inexpensive, but to get a unit that does tabloid size (that's the max for all lasers right now) will run over $1000.00
Dry Film Imagesetter - Good stable black film....but it's expensive. The OYO's most inexpensive machine ($4000??) is only 300 dpi - So halftones aren't the greatest. The film comes in rolls and runs about $2.50 a square foot. It's 12" wide by whatever length you need. No chemicals involved - No mess. I know a lot of printers who use this system. They're happy with the quality of the film but complain about running cost and width limitations. OYO has bigger machines - I saw one in St.Louis a few years back.60" width - $75000 - Not for the faint of wallet!
Real film imagesetter - Perfect film , Perfect registration - but really expensive. A new setup can set you back over $80000. There are lots of used units around (Offsetters are switching to "direct to plate") and you can get a good setup with Postscript 3 for better than $10,000. Drawbacks are again price and keeping on top of the chemicals. (Developer has to be dropped at least once every 2 weeks). This is what I use but I'm making probably 100 screens a week. Obviously you have to have the need to justify the price.
The fifth and NON film option is going direct to screen. There are a bunch of different types.
Inkjet your image onto a coated screen. You burn and wash out.
Inkjet the emulsion and image onto a bare screen. It's ready to go when it dries.
Laser expose a coated screen. You just wash it out.
These are bleeding edge expensive - Down the road they'll become less costly but for now, you really have to produce a lot of screens to justify one of these babies.
Since we've all gone digital, film has become a bit of a pain for the smaller shops who can't justify some of the more expensive devices. There really isn't any one great common solution at the moment. It's really about how much can you afford to spend.