I am joining the chorus here to recommend you surprise her with her choice. If you have a specific budget in mind, you could always give her money with a card telling her it is for a sewing machine and supplies.
The service at sewing machine stores can be an important element to consider when purchasing a sewing machine. What is their reputation online and in the local sewing community? If there is a problem, will they service the machine at their own shop, or will they send it out? Would you need to pay for shipping for repairs done during a warranty? How much do they charge for basic maintenance on that machine compared to other shops in your general area? Are they knowledgeable about sewing? Do they offer sewing classes? How long have they been in business?
Also, even if there appears to be a good deal, it might be better to sleep on it before taking the plunge into ownership. A night of research can be very convincing one way or another when shopping for sewing machines. There are plenty of reviews online and videos on YouTube. If a readable manual is available online, I think it is worth the time to read it. Prices of desired accessories can be researched, as well.
For me, I prefer vintage Bernina mechanical machines with knee lifts and needle-up features. Most sewing machine shops have pre-owned machines, too, often serviced and including a warranty. Used is used, so these are not for everyone. Personally, I have purchased about 16 used sewing machines in the past two years. In general, sewing machine brands that draw me are Bernina, Juki, Janome, Pfaff and Babylock. Of these, I do not own a Juki, nor a Babylock, but I would buy one. I like my old Kenmore machines, too, some made by Janome. Everyone is different. Some people keep an old (or new) mechanical machine for certain work, and have a computerized machine for other work. That could be an option for your wife, too. Good luck, and please keep us posted!