Types, replacement issues and style ideas
Mobile home windows are generally described as horizontal sliders, vertical sliders and jalousie. Jalousie are the old style and not used anymore. If you are replacing windows you will need to know which style you want and be prepared to tell the supplier the hole size. By that they mean the size of the hole in the wall when the window is removed. They come in standard sizes and no one expects exact fits. To get a good approximation of the hole size without removing the window, measure the window from wood to wood on the inside of the home. Don't include any trim if it is present, and especially don't measure the flange on the outside of the home.
If you are thinking of replacing windows, increasing the size of the opening at the same time will really brighten up the interior of older homes. If you increase the distance from top to bottom you don't have to get into the supports or worry about load bearing areas. Check with the suppliers to make sure you can get the size you want before you take anything apart.
If window replacement is not in the budget, window blinds or shades may be a solution. They come in a variety of materials and textures with prices from inexpensive to VERY pricey. Discount stores all carry vinyl mini blinds in a variety of colors and sizes. If none of the standard sizes will fit, slightly more expensive varieties are available in a "cut to fit" product. You provide the measurements and the clerk uses the store trimming machine to cut them as you want.
One issue in locating replacement windows comes during shipping. Shipping costs easily become a major portion of the total cost due to the unfortunate combination of weight, size, and breakability. The other practical reason that many parts places are reluctant to ship windows is the problem of returns. Even experienced installers occasionally mis-measure the hole size and have to exchange the window. This is more challenging if your supplier is 2000 miles and a week of transit time away. As one example of shipping costs, on a $40 window, the estimate for shipping was nearly $90. Shipping on two windows was the same as for one. Replacing multiple windows, splitting an order with a neighbor, or having concerns other than price will help you get what you want.