Good luck on your purchase. I have not had much luck working out price reductions with the builders I have represented my buyers for. In some cases we were able to get some very minor cost reductions but any more substantial concessions came in the form of incentives and even then not much.
My advice to you is to try every trick in the book to get some money out of them. Walking in with a group of people and getting a few purchases is a great idea. Asking for MR or HOA costs is also a great idea. Ask for any and as much as you can. Will the builder accept? Maybe and maybe not but it doesn’t hurt to try. Your best leverage would be leverage you develop over time. The more guts you have to look the sales lady in the eye and make a demand and walk away if they don’t meet your demand, then the more you may get in the long run if you are in it for the long run. That is, you can accept walking away and then coming back a few months later.
The bottom line is that for the builders, the last thing they will do is lower the sales price. They will much rather give incentives, upgrades because the cost for them is much less then they give back to you right? They may claim they are giving you 50k in incentives or upgrades when in reality it may cost them 40-60% of that in materials in labor… but what can you do. Also getting credit for MR and HOA is fantastic. Get your realtor to kick you back a rebate of some of thier commission as well to you and make sure your realtor is with you if you go to the sales office for the first time to register. If you don’t have a realtor then ask the builder to give you the commission they would pay your realtor in the form of an HOA or Mello Roos prepayment or something like that. They may punt on that but if you don’t ask you don’t know.