Cheap in this category means narrow, not worse. Every tool below does one job well and expects you to bring the rest. The expensive platforms bundle data, sending and reply handling into one bill; these unbundle it, and the total is usually still lower.
What you give up is sourcing and reply handling. You will write your own sequences and find your own list, which is work, and which is also how you learn whether the motion works before committing to a platform costing forty times as much.
One warning applies to all of them. Cheap sending tools make high-volume outbound survivable, not advisable. If your reply rate is under 2% on a clean list, the constraint is the offer, and no amount of sending capacity fixes it.