Making do with less is a sign of the times, but when it comes to your sweetie, you really want to make her Valentine's Day special to show her how much you care. How can you do that when you're on a budget?
Spend more time and effort instead of spending lots of money.
Carefully arrange for a fabulously romantic dinner at home. Show her how much you care without buying anything but the food and the wine, it'll be less expensive than a restaurant, and if you take the time and care to set the mood, there will definitely be romance in the air!
How? Tell her she has to disappear for the later afternoon or early evening on Valentine's Day so you can prepare for her surprise. That will have her anticipating something special, and set the stage for your evening.
Before the big day, do the preparation. Make the arrangements to farm the kids out to grandma or a friend, scope out the linen closet for the right tablecloth and napkins, make sure there are plenty of candles and candleholders to create the atmosphere, have the silver and glassware polished, and check out what might be available for dinner. If you're not yet married or living together, give your space a good cleaning the day before, and make things shine. If you don't have nice linens or china or glassware or good silver, borrow them from a friend or family member.
If you aren't the best cook in the world, see what's available in the gourmet section of the local supermarket that can be simply popped in the oven and cooked for a set amount of time, and supplement it with fresh greens, some prepared and ready to heat side dishes, and a killer dessert. Pick these up the morning of Valentine's Day so they'll be fresh and tasty. Keep her preferences in mind, and buy the seafood she loves even if you prefer the steak.
If you can cook, make the effort. Keep it simple and elegant.
Whether you buy prepared foods, or do the cooking yourself, remember that presentation is as important as the content. Take the time to make things look wonderful. How? Check out http://gourmet.com or http://epicurious.com and look at the images of the dishes. How do they garnish? How do they use the sauces on the plate? Now use your imagination and do something similar. It's amazing what you can do with a sprig of fresh herbs and a couple carrot curls, or a dash of wasabi across the plate before placing the entree.
Valentine's evening, meet her at the door, showered, shaved and dressed nicely. Take her coat. Make her feel pampered. Kiss her passionately, then lead her into your carefully prepared candlelit table setting. Have the lights low. Have some soft music playing, and make sure it's a song that means something to her. Pull out her chair. Then tell her you love her. The rest will come easily.