I haven't run Hell in Freeport yet, but here are some ideas I've used in other games.
I used to own a lot of metal minis, but never used them much because I didn't have the time to devote to painting them. (I've since passed the bulk of them on to someone who does.) I got more use out of the cardboard counters from the old 1st ed. Battlesystem boxed set, because they were often easier to differentiate, transport, and sort than a mass of unpainted minis.
When I joined a roommate's AD&D game a few years ago, I used those counters and some of my minis to supplement his meager collection. Telling the PCs and NPCs apart was sometimes a problem, so I struck on the idea of using my LEGO figures (mostly Castle sets) to represent the PCs. This was a hit, and I've been doing it for most games I've run since. At least two other GMs I know have adopted the idea for their games.
In games I GM now, I use LEGO for the PCs and for important NPCs and monsters. (I've figured out how to make centaurs, minotaurs, and giant cobras, among other things.) For the rest, I use a combination of Cardboard Heroes (SJ Games), those old Battlesystem counters, and a random collection of cheap plastic animal toys accumulated since childhood.
The Castle, Star Wars, Adventurers, Ninjas, and Harry Potter sets are your best bet for materials for making your own D&D LEGO minis: "medieval-ish" bodies, headgear, hair, weapons, & accessories, plus lots of animal figures.
Suggestion for a LEGO Jalie (based on the HiF cover): Start with a Darth Maul or Emperor Palpatine body, cloak and cowl. Replace the head with a skeleton's skull. Make him taller by sticking black 1x1 bricks on his feet, then put him on a 2x3 (or larger) flat base for stability. Use two of those 1x1 flat pieces with the protruding clip to extend the arms and give him claws; the bottom of the 1x1 part will snap over the non-tapered side of the hands. (He can hold weapons this way, but be careful not to snap off a claw moving him around the table.) If he still doesn't look tall enough, stick a 1x2 brick between the torso and legs.