One of the biggest challenges in developing e-Learning is to create visually appealing work with little or no money. There are millions of sources online that you can draw from for your visual images, however the legal use of these images is something you need to consider before you publish to your audience. Using a photographer's work without their permission and without paying the appropriate license fee is copyright infringement.
Some of my collegues have tried to claim that using a photo from the Internet in an e-learning course, can fall under fair use laws. This is only sometimes true. If you were teaching your audience about a company, you can use their company logo and claim fair use. You could not use a photograph of their CEO taken by a photojournalist, nor could you use a funny comic strip about that company without paying the appropriate license fees to the original creators of those materials. There are balance tests that a court would use to determine if fair use applies to each individual case, however you don't want it to get that far.
Here are some great resources for multimedia that may be helpful for those with little or no budget to spend:
Wikimedia is a collection of multimedia that for the most part is open and free to use without individual permission. The multimedia ownership is retained by the individual creators. Check for the particular license for each item to ensure that your planned use is acceptable.
Love Vector Free is an excellent site for vector graphics. The files will be in .AI, .SVG and .PNG formats which can be opened in most professional graphic editing software such as Adobe Illustrator or Photoshop.
MorgueFile is a site dedicated to free photography. In most cases you can reuse their material within your work, however it cannot be used on it's own. You may be able to modify much of the work, so cropping out parts of the photo that you do not need can be considered acceptable.
Turbophoto maintains a small repository of free stock images that you can download and reuse. The selection isn't vast, however you can add this as a source in case you are designing material that happens to fit one of the ten or so topics they cover.
4FreePhotos is an awesome site that is maintained by photographers who just love taking pictures and getting them out there. The site seems to be funded by lots of ads but I don't mind this as the photos are all free.
Stock.XCHNG is another great resource with a very large number of photos. They do require an account setup with a login and password, and you will need to read their license agreement for the photos you download as there are some restrictions.
Of course last but not least, almost everyone owns a digital camera. If everyone in your training department took a dozen or so pictures each week to contribute to a team multimedia database, you would find that you would have a large stockpile of free to use images or videos in fairly short order. Take pictures of your companies building, your competition, products that you sell,and more. Since you own the pictures you will never have to pay royalties or license fees to anyone.