No, it doesn't.
With the MMP model proposed, we'd have the same number of representatives as what we have now.
Currently we have 27 MLAs. With Mixed-Member Proportional (MMP) the Island would have 18 district MLAs and 9 province-wide MLAs, totalling 27.
Since the number of representatives would likely not change, the overall cost to pay representatives would be the same too.
To put things in perspective: the budget for PEI's Legislature is only about 0.5% of the province's annual budget for things like healthcare, education and infrastructure. The legislature is the decision-making body for how approximately $1.7 BILLION of our taxes should be spent. With proportional representation, we have more transparency and better oversight over how that money is spent. That's where the real savings happen!