Fruit Salad Tree
If you are short on space and still want to grow your own fruit and don't want to settle for just one type, you may consider a 'Fruit Salad Tree.' Other varieties come under the name 'Fruit Cocktail Tree' and 'Fruit Bowl Tree' etc. The 'Fruit Salad Tree' originated in Australia to economize the growing of fruit for small spaces by grafting multiple fruits on one tree. There are multiple apples, or stone fruits of peach, nectarine, plum, apricot, etc. or even citrus with oranges, lime, lemon, grapefruit and mandarin. Depending on the grower, these multiple fruiting trees can have 3-8 different fruits on one tree. Not a 'Fruit Salad Tree' but following the same idea are multi-grafted avocado trees that are self pollinating and prolong harvest.
Locally I have found the like at Yamagamis on De Anza Blvd. in Cupertino and the Summerwinds on Almaden Expwy in San Jose. Other nurseries may also carry them if you call around and they may be available to special order if not in stock. I caution the purchase over the internet since you have no idea what you will get and if it's tiny, it will be more difficult to raise and take longer to get fruit. At a nursery, you will see what you are getting and may have some warranty if directions for care are followed. You can order directly from the Fruit Salad Tree Company in Australia. They have trees for cold or warm weather. Shipping can be up to 18 months depending on order.
Another consideration is 4 in 1 trees. Four varieties of one kind of fruit grafted onto one tree. It can help cross pollinate and gives a longer harvest period without too much fruit all at once. Almden Valley nursery tends to have many type sin stock. God's Little Acre tends to have them year round. Both nurseries are located in Almaden Valley of San Jose.
So if you want many different apples, many different stone fruits or different citrus and don't have the space for all those trees, one or all three of these may be a solution!