For your shared node, look into crowdnode.io. I'm sorry, but shared nodes are stupid and lowering the amount needed for a mnode significantly will never happen, we don't need minnows running mnodes, those are for people with serious money to invest, because it is a high risk venture and requires a lot of your attention, the last thing DASH needs is an army of minnows not giving a poop about the DAO because their investment in it is so low.
Perhaps trustless shared masternodes could be implemented in a way where someone could signal to the network they will run a masternode in need of collateral and anyone with DASH could delegate their share to the masternode collateral contract. Then the masternode owner and everyone who delegated some DASH could get their cut of the reward when the masternode gets paid. Also, voting could be done in a way where everyone could have a voice in proportion to how much DASH they delegated and the masternode would vote on each proposal whichever way the majority of their delegators did.
I think this would be a good solution for Dash.