There are many ways to save money when scrapbooking your vacation memories. 
First of all, while of vacation, collect brochures and low cost or free postcards whenever they are available to you. You can typically find postcards of your hotel/motel in your room and low cost or free post cards are usually available many different places. Other things to look for while you are on vacation include match books/boxes, coasters (disney provides many of these in their resorts), packaging of toiletries, packaging from your sourvenirs, tickets and or passes for events or parks, maps and/or brochures, and free or low cost pins or stickers. For instance, Disney cast members pass out lots of stickers in the parks and at their shopping destinations to children and customers who request them. Another good place to get low cost or free items for your scrapbooking is roadside stops and airports. Look for kiosks and information counters that provide brochures about local attractions, etc. At many locations you can also get maps of the area you are visiting and this can be a wonderful part of your scrapbook pages.
Next, take lots of pictures each day and from be sure to include each place or event you attend. Another thing you can do is to journal during your vacation and then either type those memories up and place them in your scrapbook or if you prefer use the actual written page in your scrapbook. Pictures and recording your experiences are the most important part of creating the scrapbook.
Next you need to decide how detailed you want to be with your scrapbooking, are you going to only show the highlights or are you going to document each part of your trip in detail. Are you going to have an entire scrapbook that shows your pictures or are you going to just complete a few pages in an existing scrapbook. Once you have decided how you plan to use the pictures and journaling and have incorporated the free stuff or low cost stuff from your trip, now is the time to look for embellishments to finish that page. Most scrapbooking stores have stickers, die cuts, paper and other embellishments that you use to accent your page.
Last of all, remember that there is no right or wrong way to scrapbook your vacation. The most important thing is to include those memories that will make you smile and help you remember the important parts of your vacation.