MinMaxSliderAttribute.cs

using System;
using UnityEngine;

[AttributeUsage(AttributeTargets.Field)]
public class MinMaxSliderAttribute : PropertyAttribute
{

	public readonly float max;
	public readonly float min;

	public MinMaxSliderAttribute(float min, float max)
	{
		this.min = min;
		this.max = max;
	}
}

MinMaxSliderDrawer.cs

using UnityEngine;
using UnityEditor;

[CustomPropertyDrawer(typeof(MinMaxSliderAttribute))]
class MinMaxSliderDrawer : PropertyDrawer
{

	public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
	{

		if (property.propertyType == SerializedPropertyType.Vector2)
		{
			float textFieldWidth = 30;

			EditorGUI.LabelField(position, label);
			Vector2 range = property.vector2Value;
			float min = range.x;
			float max = range.y;
			MinMaxSliderAttribute attr = attribute as MinMaxSliderAttribute;

			Rect sliderPos = position;
			sliderPos.x += EditorGUIUtility.labelWidth + textFieldWidth;
			sliderPos.width -= EditorGUIUtility.labelWidth + textFieldWidth*2;
			EditorGUI.BeginChangeCheck();
			EditorGUI.MinMaxSlider(sliderPos, ref min, ref max, attr.min, attr.max);
			if (EditorGUI.EndChangeCheck())
			{
				range.x = min;
				range.y = max;
				property.vector2Value = range;
			}
			EditorGUI.LabelField(position, "");

			Rect minPos = position;
			minPos.x += EditorGUIUtility.labelWidth;
			minPos.width = textFieldWidth;
			EditorGUI.LabelField(minPos, min.ToString("0.00"));
			Rect maxPos = position;
			maxPos.x += maxPos.width - textFieldWidth;
			maxPos.width = textFieldWidth;
			EditorGUI.LabelField(maxPos, max.ToString("0.00"));
		}
		else
		{
			EditorGUI.LabelField(position, label, "Use only with Vector2");
		}
	}
}