You mention small production above - how large?
Because, before we go anywhere talking about any specific machine or approach ... it is very helpful to have an estimate of your bar production needs? Hundreds per hour? Hundreds per day? There is a huge difference in how I would recommend approaching this depending on the production volume you are talking about.
That said, one of the nice things about flood/scrape mold loaders is that you can fill different mold configurations without having to adjust anything in the line (assuming all the molds are the same size). The downside is that the method can be very messy and it does not handle mixed-in inclusions very well.
Pneumatic depositing options fill each mold cavity separately. They are more expensive, but the process is much cleaner. That's an advantage when going directly to a cooling tunnel as excess chocolate on the outside of the molds can get caught up in the drive mechanism.
You can DIY a cooling tunnel using a series of chest freezers bolted together. Remove the door (lid) and build a wooden collar (8-12 inches high) on top of each unit (this is done all the time for jockey boxes for craft beer to hold the taps), then attach the door to the top of the wooden collar.
Create openings in the collar for the conveyer to fit through. Put a PID control unit in each freezer to control the temperature of each unit separately. Put a fan in each unit to move the air around inside (you can build internal baffles to direct/control the airflow). If humidity is a problem, put a dessicant inside each freezer.
3, 7-foot chest freezers give you the base for a ~21-foot tunnel for well under $5000. PID controllers are going to be less than $100 each. I don't have a price for a conveyor unit but you want a surface that will allow air flow underneath the mold and you want the speed to be adjustable. You want the conveyor to be at least 18" longer on each end (3 feet overall).
21 feet is approximately 7 meters. If the belt speed is .5 meters/minute then a mold will spend about 14 minutes in the tunnel. If you are using 275x175 molds then the max throughput is just 3 molds per .5 meter so you're talking about max throughput of less than 3 molds/minute. If you need to work faster you need a longer tunnel.
With separate PID controllers you can set the temperature of each freezer differently. If ambient is 68F you could make the outside units 62F and the center unit 55F (I recommend an odd number of units for this reason). Of course, you can make this any length you need by selecting different freezers - though they should all be the same dimensions for obvious mechanical reasons.
clay - http://www.thechocolatelife.com/clay/