Rodney is right. I would not touch this job for less than $5.50 per shirt heat pressing. I am a bit nervous for you with this large order. I hope you know what your doing. I do use Iron All Transfers which are very delicate to use and I almost have to hand feed them into my printer (Epson) because they stick together. For dark shirts I am using Coastal Jet dark.For a heat presser dark colors are a challange. Even though I only do heat pressing if someone came to me and only wanted words on dark shirts and not picture designs I would find a screen printer or get someone to do Plastisol transfers done as I am doing for a school order.