If you know he really wants to get you a new machine, I suggest you research machines and give him the make and model of the one you want (you might even include a picture and the name of the store where he can buy it). Then, he will know exactly what you want and can make the choice of whether to get it or not.
Bless him, because his heart is in the right place. You just have to point him in the right direction.
My DH has always been supportive of whatever hobbies I took up. I never had to sneak anything in the house. When my tried-and-true Singer Fashionmate had her 30th birthday, I started looking for a machne with more bells and whistles. DH handed me $1,000 cash he'd been saving (for what, I don't know) and said "Use this to get what you want." When I called and told him I'd fallen in love with a Bernina and it cost $3,000, he swallowed hard and said Go For It. Of course, a man who has spent $10,000-plus each on several hand-craftted guitars is not going to tell his oh, so, understanding wife that she can't spend $3,000 on a sewing machine! Or that she can't have a "new" Featherweight, or a "new" treadle machine, or a "new" . . . you get the idea. In fact, one of his friends was getting rid of a 1929 Singer Model 99, and he told the friend that I sew and quilt and he would buy the machine from him. The friend said that if I'd give it a good home, he could have it. It doesn't work, but it looks great on the shelf!