You will need to budget a lot higher.
Some specs to look for, in addition to the minimum specs of the software you use:
--CPU clock speed is important, the higher the better. More cores will help with rendering speed. I would recommend a clock speed of at least 3 GHz "turbo", with 4 cores. This will typically mean an Intel Core-i7, although you can get away with an i5. You can compare Intel CPUs
here.
--Get as much RAM as you can. I would consider 8 GB minimum. Keep in mind that, depending on the laptop, you might be able to install more yourself.
--A dedicated GPU is a plus, if you can afford it. The newer Intel HD integrated graphics are getting a lot better though. Intel Iris integrated graphics are better, with dedicated Nvidia/AMD the best option. The gamer GPUs (GTX/Radeon) will work, but a workstation GPU (Quadro/FirePro) are more optimized for CAD. These are typically found on the more expensive business laptops. Keep in mind that integrated graphics will use system memory for graphics data.
--A SSD for storage will drastically reduce the time it takes to load the software and load/save a large model. They are expensive, however, and may not fit in your budget.