soil block making although fun and gooey is real work. making the mix is not the real trouble it is coming up with the ingredients. we have jumped in both feet first. we already own two sizes of the makers. we have one seedling small and the other matching medium size. the medium block receives the small block like a puzzle piece. we have bought all the ingredients. not too pricey if you consider the cost of purchased seed starting stuff and it is easily paid for. most frugal people would just use their compost and call it good. this method is not for them.
our first batch of mix has revealed that my compost* this year has too many interloping weed seeds. compost is one of the ingredients of the mini block. this unsterilized compost is also likely the cause of our damping-off. so for this round we sterilized my compost in the oven. this batch was easier to make with better results. practice makes "better"..
so far we are happy with this method especially since we plan to sell seedlings this year. but, be warned this is no panacea. it takes some effort but the results seem elegant. we have had good germination. the tightly packed lightweight soil seems to have great capillary action and keeps the seedling properly moist if the block is kept properly watered.
another caveat is the blocks must be watered several times per day. we bought a mist sprayer and it has been instrumental in keeping up with watering. here is a pretty good video of the soil block maker.
* my compost is not scientific. i just pile the mix of manure and brown stuffs into some pallets. i let it decompose for six or more months. laboratory style composting might produce sterile enough compost but i already have too much going on. my garden really likes it and that is enough for me.