When I have talked to moms considering it but wondering about the benefits and the costs I have them do a cost comparison. If you have kids of your own then it almost always works out in favour of staying home.
Take the amount you make working as in your take home amount, subtract the cost of daycare for your own kids, the cost of transportation to work, half the cost of lunch out if you buy, a portion of the money spent on clothing for work and upkeep such as drycleaning. Subtract a portion of your grocery bill if you eat out a lot or buy convenience foods because you don't have time to cook after work.
The result is the amount of money you need to make in childcare to equal what you made at your old job - which usually turns out to be not very much. Divide this amount by the daily fee you plan to charge and that gives you a pretty good idea of how many children you need to have in care to make ends meet. If it is more than 3/4 of the allowable limits for your area then it could become stressful at times of low enrollment since there isn't a lot of ground made up when full so something to consider.
If your calculations are totally to your advantage that can help with your arguement. I have four kids so if I had had to find daycare for them all plus work there would have been very little take home pay for me.
Ask him what his concerns are. What is it about the kids that concerns him. I am assuming you have kids of your own so they must have toys and must play somewhere in the house. There are lots of ways to have a daycare during the day and a family home evenings and weekends. You don't have to have a large playroom with fancy decorations and such.
I know some that have two kids and moved the two into one bedroom and then turned the other bedroom into the playroom. With time spent outside, in the kitchen for meals or gathering to sit in the middle of the livingroom for circletime/storytime having only a small bedroom for freeplay will still allow you to offer a full program but close the door on it at night - out of sight out of mind for hubby. It comes and goes while he is gone to work.
Do you have any friends that provide daycare that have husbands that would talk to your husband about his issues, maybe able to reassure him that it can work.