Much of the effort spent getting a home which you like has to be done by you before talking to either a builder or sometimes even a real estate agent. You have to know what you want and how much you are willing to pay for it. Once you have created your want list, pick an experienced realtor, meet with her, and review your desires with what she says is typical for the areas you would consider moving to.
Unless you are wanting something unique, a home which already has most of what you want will probably be your best buy. If you think you will be wanting a bigger house in the future then you should consider how any house you buy now could be expanded. I recently sold a home in a nice Palo Alto neighborhood which had one bedroom significantly wider than is typical. A hallway could be put through that bedroom and a new master suite built at the end of the house. The resulting floor plan would be as good as if it were the original plan. It is an excellent home to use now and then expand when needs and finances make expansion a good option.
One of the benefits a good architect provides is making sure that his final design fits your dreams and budget. Reaching this understanding takes time and thus money. An architect can not visit an existing house and give you a great remodel design and budget in an hour or a day.
I had a home custom built for me and posted many of the steps on my website.
I am very happy with both my architect and my builder. I am very happy I built a new home. However it took a significant commitment and I would not blindly recommend that everyone who wants to, should remodel or build a new home.
The price of a stove for a kitchen can vary from perhaps $500 for a cooktop to $10,000 for a professional range (or higher). Other appliances can also easily vary by 400% in price. Some very rough numbers for additions are $10,000 for a bathroom and $30,000 for a kitchen (fairly low end) but cabinet costs, tile work, etc will vary dramatically if you match the quality these to the quality of the appliances. You have to be prepared to ask fairly specific questions to get answers which will help you decide.
I am currently working with a family who just bought a home and are trying to decide how much remodeling they want to do before moving in. Perhaps their biggest decision is whether to remodel the kitchen now or later. When they remodel the kitchen it would be most effective to move the washer and dryer. However if they move the washer and dryer, they should build a new master suite. As you can imagine the decisions are unique to each home and each buyer. General advice can only give you a pointer towards what questions to ask.