If you want cheapest and single sitting treatment, than tooth color composite space closure is the only option. A better treatment option is crowning your 2 front teeth. Veneers cannot close "big gap". Crowns are long lasting and enhance your smile. Zirconia crowns are best, both in terms of esthetics and strength, but they are very costly. You can get PFM crowns, which have acceptable appearance and are economical. Composite space closure is least expensive, but remember it wont stay for long, moreover, it tends to stain. If you have just spacing problem in your midline front teeth, than it can be closed using removable orthodontic appliances, which are not expensive, but if your upper lip
muscle attachment is very low and thick than this treatment is not for you. Remember braces treatment for space closure is of short duration, i.e around 6 months, so the cost of this treatment is low for you. Braces is the best treatment, as it will shift your natural teeth to desirable alignment.