Plan your spending ahead. What do you expect your landscaping project to look like? Divide into a series of small projects.
Start with a rough sketch of how the project will be laid out, such as flowers on one side, shrubs and bushes here and there. If you are planning to add large trees such as Pine, they will require a lot more room and consultation with a professional tree expert when deciding which trees will grow best in your climate while taking the size of your lot into account.
Purchase in phases, timing your buying in steps will make it more affordable. Be flexible as seasonal bargains may appear.
Strive for quality, as the cheapest plants are not always best. Garden centers at big box stores usually do not take care of plants as well as greenhouses do.
Check plants carefully, as plants which are diseased by some fungus, or by neglect will not last long, so more budget money is needed for replacement.
Check other sources. There is a universe of plant and landscaping information on the internet, plus many online and mail order seed and plant sellers. It may be a surprise to find an unknown source of garden plants and supplies near you.
Neighbor cost sharing. If you have amenable neighbors, perhaps you can share whatever you can buy in bulk. Sharing any lawn tools that are not used often, plus renting any necessary equipment now and then adds to savings.
Many people use hardy Cactus plants for landscaping. The Cactus plant family offers many varieties while needing little care, and sprout beautiful flowers when in bloom. Just beware of the prickly spines on Cacti, always wearing gloves when handling them.